Is it me, or are iTunes and iPods terrible at playing random?

I’ll have a play list going, about 50–75 songs long. I have a few favorites that I like to hear more than others, but generally, I just let it play through. But then it seems that sometimes the playlist will just never randomly play those songs I want, so I feel like I have to skip forever until I get it again. That and the play list will play songs more than once, but neglect my favorites. Anyone else have this happen? or is it just my imagination?