Tats are definitely sexy as long as they ain't some crazy satanic 1s or something for me and most guys I know, if a girl has her sleeves tatted its a rap. That is the sexiest ink a girl can have. But piercing can tend to be too much sometimes. A few here and there is all good, but when they have their face pierced its an automatic turn off for me.
I personally like peircings, such as belly rings, lip rings, nose rings, and ear rings. As for ink, its not what I look for, but I can deal with smaller ones, like tramp stamps. But anyway, I would say they can be a turn on.