It depends on the situation. I'd be pretty pissed off if a girl ****ed me just to give me some kind of disease. I'd probably be pretty mad if she knew she had it and didn't tell me because she thought it'd make me mad.

My face would be red if I had one, didn't have any of the tell-tale signs, gave it to my girl, and then got the signs when I got it back. Man, that'd suck.

All in all, I think it depends on honesty and the severity of the disease. If someones withholding something of that magnitude, I think it would warrant a nice long conversation. If they're lying about having one, it's a total game changer and relationship ender... and if they have anything ridiculously serious, then there's a good chance I wouldn't be around in the first place.