Where has your mouth been!!? Hesitant about kissing my dates : (?

I'm a hypo-chondriac (spelling?) Im a germaphobe as well. When I'm on a date with a guy, no matter how well it has gone, at the end of the night before the kiss.......I'm always thinking "oh gross. Where has your mouth been?" I never know whos been munching the carpet of various sluts. lol. Does this happen to anyone else?