...and I was given a cutter to open it. Some people, especially those who ask for a new piece of clothing that they are going to purchase, feel it's important to have a brand new watch that has not been manhandled or tried on. Most would prefer that a leather strap watch that they are going to buy hasn't been worn by others. Whilst most AD I know would not allow shoppers to try on watches on straps, it's sometimes difficult to reject a VIPish or regular client who has bought many watches there before.
In the end, if was a reputable AD, you need not be worried if an unsealed watch was anything less than a brand new piece. If you are anal about the virginity of your timepiece, by all means, request for the hymen, uh I mean - seal - intact --> from what I know, many of the higher-end usually undisplayed Pateks are sealed virgins anyway.