Copying a relevant answer over from Is it permitted to look for a job while visiting the US under the Visa Waiver Program?:

Yes.

From the US Embassy in Australia’s website:

Question:

Can I travel to the United States on the Visa Waiver Program to find a
job or attend interviews and then apply for the E-3 visa once I return
to Australia?

Answer:

Yes, you can travel on the Visa Waiver Program (VWP) if you meet the
requirements (please see our page on the Visa Waiver Program). If you
do not meet the VWP requirements, you may be eligible to travel on the
B-1/B-2 Combined Visa for Business or Pleasure.

You must leave the United States before applying for your E-3 visa.

Although the question is about VWP, the answer additionally mentioned that a B-1/B-2 visa can also be used for this purpose (to find a job or attend interviews).

As we speak I am sitting in LAX waiting to return to Melbourne as my partner was denied entry today (and has been held in immigration for 15 hours and basically treated like a common criminal) because she declared she would be “looking” for work whilst in the USA on an ESTA. We took advise from the USA Embassy website which said that you can look for work on an ESTA, however you will need to leave the country to apply for your VISA – as you can appreciate this was not the case according to immigration. Interesting that the embassy and immigration would suggest two completely different things.
The lesson from this “lie, lie, lie” – apparently the USA would rather you be dishonest and just tell them you are here for a “holiday” as opposed to telling the truth to which they deny your entry.

I stumbled upon a similar problem about a month ago. There were no clear answers on any of the official web sites. So I emailed my local consulate asking them if it’s okay to apply for a B1 visa for the purpose of attending a job interview.

They said that it’s okay and I can apply for a visa. So I brought an informal invitation letter from the company and I got my visa approved.

On the border I stated that the purpose of my visit was a job interview. Got usual 6 months.

However, as I mentioned, I had an invitation letter. I suppose that if you want to look for a job while in the US, the rules might be different.

Based on my experience, I would say that asking you local consulate via email might be a good idea. They are typically very responsive.

Contrary to the allegations of some other answers here, CBP (U.S. Customs and Border Protection) does not make up rules on the spot. Here is, quite literally, the letter of the law on who’s allowed into the US and who’s not:

INA: ACT 212 – GENERAL CLASSES OF ALIENS INELIGIBLE TO RECEIVE VISAS AND INELIGIBLE FOR ADMISSION; WAIVERS OF INADMISSIBILLITY

The vast majority of that is about criminal records and whatnot, but Section 5a is key for us:

Any alien who seeks to enter the United States for the
purpose of performing skilled or unskilled labor is inadmissible

Boldface mine. In other words, if you give CBP reason to suspect that you’re coming to the United States to work on this visit (say, a plumber rocking up with a box full of tools), you will be denied entry. But you are perfectly within your rights as a tourist or business visitor to enquire about future employment, go to interviews, etc, as long as a) you’re not paid money for it, and b) you leave the United States and get a proper work visa before you come back.

Also, as long as your primary purpose for visiting the US is tourism, it’s not a lie to state your reason for entry as “tourism” and then do a little job-hunting on the side.

On the official US government site "Travel.State.Gov" is relevant information

Visitor Visas – Business and Pleasure / Overview

Generally, a citizen of a foreign country who wishes to enter the
United States must first obtain a visa, either a nonimmigrant visa for
temporary stay, or an immigrant visa for permanent residence. Visitor
visas are nonimmigrant visas for persons who want to enter the United
States temporarily for business (visa category B-1), tourism, pleasure
or visiting (visa category B-2), or a combination of both purposes
(B-1/B-2).

Here are some examples of activities permitted with a visitor visa:

Business (B-1):

• consult with business associates
• attend a scientific, educational, professional, or business convention or conference
• settle an estate
• negotiate a contract

Tourism and Visit (B-2):

• tourism
• vacation (holiday)
• visit with friends or relatives
• medical treatment
• participation in social events hosted by fraternal, social, or service organizations
• participation by amateurs in musical, sports, or similar events or contests, if not being paid for participating
• enrollment in a short recreational course of study, not for credit toward a degree (for example, a two-day cooking class while on
  vacation).

These are some examples of activities that require different categories of visas and cannot be done on while on a visitor visa:

• study
• employment
• paid performances, or any professional performance before a paying audience
• arrival as a crewmember on a ship or aircraft
• work as foreign press, radio, film, journalists, and other information media
• permanent residence in the U.S.

^{(Second part added from the same source by hippietrail, was not present in original answer.)}

This is absolute drivel. Sad this comes up as the first post on a google search on this topic. So tell me how does one logically come to the USA for a job interview?

It is absolutely OK to travel to the USA on a Tourist visa if you intend to ‘look’ for work or attend interviews. If asked at the PoE, you state your purpose. I have done that twice now. They typically give you much less than the usual 6 months – say 3 weeks each in my case when I attended interviews for only 2 days. Just be honest about your intentions.

Searching for a job

No you can most definitely not legally look for work while on a tourist visa.

If any evidence is found that you are looking for a job you will be denied entry on arrival or could risk deportation at any time.

Things that I’ve heard of US customs using to deny entry or deport travellers:

• art folios
• diary entries mentioning job offers or looking for work
• letters of introduction, curricula vitae, resumes
• samples of your work
• tools of your trade

If you are randomly selected or if you fit some profile they may suspect you of looking for work and specifically look for these things.

For deportation I hear the single biggest reason is being reported by somebody. So if you do entertain the notion of looking for work even vaguely during a tourist trip, don’t go around telling too many random people you meet, or don’t go around giving people reasons to dislike you.

(The very same tactics apply in at least Australia and the United Kingdom by the way.)

Other sources that say you may not search for a job on a tourist visa

• tree.com Legal services article Can I Look For Work In The United States On A Tourist Visa?
  

  If USCIS feels you’ve violated your tourist visa requirements by looking for a job, it may deny your work visa and could even prohibit you from remaining in the United States on a tourist visa.

Attending a job interview

This seems to be treated as a separate case. I have no experience with this or anecdotes from friends or acquaintances. Please refer to Pablo’s answer.