I guess I should have said protein supplements with more than a few grams of fat per serving. Dymatize is pretty low fat, so it doesn't cause a problem.

I noticed that Ultra Peptide 2.0 does give me bad breath, just as bad as from Muscle Milk. Both have low saturated fat content, so it seems that the type of fat doesn't matter too much.

Wilki, I noticed that some people's bad breath emanates from their tongues more than other people's. (And as you point out, with some people the source is mainly from their stomach.)

I think the best test is to ask your significant other an hour or two after you've consumed your protein!