Even if I know more or less what I am looking for, I'd still rather do it on my own time than have a sales associate "help" me. I always feel like I am pressured in to making a decision faster than I would otherwise. If they are helping me and I do try to take my time to make the decision I always get the impression of mounting frustration at my indecisiveness. That's why I prefer sales associates who say "let me know if you need any help" and then just leave me alone.