Specialised Scales

I was reading a post and someone joked "Well i can do scales in G and C!!" And it kind implied people specialise in certain keys, get really good at them in particular! I thought this because Slash plays most of his solos on an album in the E pentatonic!! So maybe its like the first he learnt and he's way better at it. Dya think some people learn for example E pentatonic, an A major, a C minor, so they dont have to worry about moving the scale up and down and stuff. Because i find it easy to learn a scale but then sit and work out for ages how to transpose it and where the roots are and stuff!!

Actually, if you notice, the E pentatonic is cool because you can do all those cool open strings licks that almost sound like tapping (here's one of them:
-5-3-0-------5-3-0--------
-------5-3-0-------5-3-0--)

And it's pretty much the same with the A pentatonic!!

The key of a song has nothing to do with the guitar players favorite scale, but rather with what key the singers voice fits. (unless it's an instrumental of course)

I notice that when I play something in E, A or B Minor (or their relative majors, G, C, and D), I can play all over the fretboard never worrying about playing anything out of scale (on accident). However, with other scales I have to consciously think about where the patterns are. The more you play songs in a key (and most of the songs I played before this year have been in G, C, and D), the better I get at not having to think about it. My fingers "know" what's in the scale and what isn't, but I can always just think for a second to play in any key. People who don't know music theory well (like the other guitarist in my band, who doesn't know about moveable scale patterns, etc.) can only solo in certain keys. This kind of proves what you were saying about people specializing in certain keys.