i have taken my young children into a sex shop, when ds1 was little, in a pushchair still, dp and i when in london for a day visited a sex shop in soho, ds1 got given a little teddy bear by the shop owner, sounds innocuous enough........ said teddy bear was dressed in bondage gear
ds1 had no clue and happily played with it whilst dp and i browsed, tho when we went back to mil house who we were visiting at the time, we were made sure to put said teddy bear out of sight! 
he is now 11 and i wouldnt take him in ann summers now, well i would the front bit, but not the back of the store, not because i think its innappropriate, but because HE would be embarrased, i am sure once he is 14/15 he will probably be having a look around the back of an anne summers store himself, thats what teens do!
i think taking babies/toddlers in pushchairs is fine and most sex shops will allow you to take in that age child, however once they are say 4-5 and upwards most sex shops wont let you take them in? and i think there would be the potential for too many awkward questions/comments so i probably wouldnt do it. but i dont think it would hurt them to see it, just that they wouldnt understand it and its not necessary for them, sex toys etc are something that you learn about as a teen in a
way and quite quickly (or it was in my case) realise that they are fun 
tho i do remember being shocked to find a vibrator/dildo in my parents bedside cabinate, but then i shouldnt have been snooping their room anyway, so serves me right!