I VERY rarely pick up a guitar now, but started there years ago before switching to bass "full-time". Funny thing is that even though I hardly play guitar, my bass playing has really develolped my musicianship and I can play better guitar now than ever. I guess I've retained the muscle memory, etc to physically play, now have a bit more knowledge (chord theory, much better ear for progressions and intervals, etc). Occasionally I'll pick up a guitar and jam along or rip out a solo and it surprises people (including me). Can't say if I'm "good", cause that's relative. Compared to Hendrix, SRV, etc I positively stink but I hold my own against other players I jam with.
Funny thing is typically what happens when a guitar player picks up my bass, they have a real tough time knowing where to start. I guess guitar really IS harder than bass... LOL