score:3
No, it's fine, assuming everything else is in order and you're not trying to (for example) avoid X-days-in-Y restrictions by switching passports.
To expand on that a bit more, immigration laws are designed to control the movement of people, not passports. As long as you as a person follow all applicable laws, including declaring other nationalities and previous entries when required, using different passports for travel is not an issue. Sure, there may be Immigration officials who consider this suspicious and may ask you an extra question or two, but this alone is not going to suffice as grounds to deny entry in any country. (Contrary to common perception, denying entry to a country for a person with valid docs has to be grounded in written regulation and usually requires approvals from supervisors etc.)
And finally, for those preferring anecdata over logic, I'm a dual citizen myself and have entered a long series of countries including but not limited to the US, Canada, Japan, New Zealand, Singapore, Thailand and the Philippines with passports of both my nationalities. The only country that ever even asked about this was the US, and that's because I had two ESTAs at the same time; when I stated that I used a different passport last time, I was granted entry with no further questions.