Why is it that everytime I meet a nice guy, and begin to think he has sheeps clothing on????

Because you want it to be the case.

Girls don't want nice guys,k nice guys are pussies, and they're boring, and they don't make your friends swoon, making them practically useless.* Girls also have the problem of upside down expectation curves. They meet someone new and immediately after categorizing the 'potential mates' from the 'just friends', potential mates are then put on a pedestal. The phrase "I met this amazing guy" is one often heard from women. From a guy you will simply hear "i met this girl". Thus the period of getting to know someone is a series of disappointments for a girl, as their potential catch falls ever closer to earth. For most guys I know it's a period of jumping through hoops to keep the girl interested. But barring the psychos and the nutjobs, when a guy gets to know a girl more and more his opinion of her usually grows. (this is totally subjective, but is what I've come to observe, so no arguing).

I was involved with someone pretty heavily over the past winter and spring, and I got to sense that very thing, that any time I let slip that I was kind of goofy or that I liked country music or that I sometimes just leave my clothes draped over the chair, it was a blow to her image of the person she thought she was with. A very distressing feeling, knowing that you're going to have to break the fact that you're not perfect to someone. Didn't quite work out, as it happened, but that's another story to be priedout of me after a few beers sometime.

In a round about way I'm getting back to the quesiton at hand. Essentially you don't notice the nice guys, because theyr'e the ones who aren't good at attracting attention. Attracting attention is a skill taht I had to learn myself, and practice at it. And I can tell you , the trick is to not care what people think, and a big part of that means taht you have to turn off the instincts to drop everything and have a deep conversation with someone or talk about feelings..

* note to readers: this is not a suggestion to be less than perfectly gentlemanly to any woman at any time, and was only written for the purposes of entertainment.