Upvote:3
Part of the Hostelworld group is BedAndBreakfast World, which is a good search engine for searching B&Bs. It itself has ratings and reviews you can go through to decide what the place is going to be like. In addition to that, many (most?) B&Bs are often also listed on TripAdvisor so you should look reviews there too.
You say that B&B ratings are not standardised worldwide, but then you'll also be surprised to know that even hotel ratings are not standardised across the world. A 'five-star' in one country doesn't necessarily mean the same in another. Hence, review sites like TripAdvisor can be far more useful in judging a place. Having said that, people are more often likely to write reviews when they have a negative experience than positive so use your own judgement too.
Upvote:4
My goto tool for B&B anywhere in Canada is BBCanada.com. It has a huge range of B&Bs all over the country (77 in Quebec City alone - BedAndBreakfastWorld has 7, two of which are motels). They are divided by region, and often down to different areas of the same city. I've never had a bad experience with any B&B I've booked through them, and many of the them have been remarkable.
Different B&Bs have different amounts of information on the site. Most have photos, some have breakfast menus, some let you book online, most have links to the establishment's own website. I never worry about certifications - I just look at the pictures and the description and make my choice.
B&B are a great alternative to hotels. You are not always going to get the comfort level of a hotel (though you will much of the time) and you won't get all the ameneties and the 24hr service, but instead you will get to meet interesting people, find out interesting things about where you are visiting, and get a lot closer to the 'local' experience.