My group of friends and I tend to vent a lot to each other and sometimes about each other when something happens. I think it's good every so often because it's just that feeling of getting everything out and hoping you can change whatever is going on.
This, and actually if you can find a common dislike with someone it can actually help strengthen the bond between the two people...because it's something that you have in common. I've made a couple of friends / got to know some cool people by just talking to strangers about the petty little unimportant things that bug me. xD