You never know what the bartender used to put the lemon in the drink. Not even the orange that looks so fresh and even less the raspberry that winks from inside the cocktail.
It could have just been his hands, but are you sure his hands were clean? After asking this question the temptation to eat or bite the decorative fruit of the drink will be significantly reduced.
Not to mention the fact that the "decorations" of serving in most cases are not kept in suitable places.
The reason is simple, as they should be left in an easily visible place so that the bartender can see them and put them in the drink easily.
Garnishes in a drink are placed to give it the right taste and aroma. So if you eat them from the beginning you probably won't be able to enjoy the drink as you should.
Ps: Have you noticed that drinkers never touch them? Do they even laugh when they see them in glasses? They know what they're doing, so be careful with your next glass.