I like wine, but I'm no wine expert. Therefore this is a genuine question rather than a statement.

If I'm in a restaurant or eating on a flight and order some wine, most of the time the waiter/waitress will pour a little bit in the glass for me to taste first. Why ?

If it's to check that the wine doesn't have anything wrong with it, then surely it doesn't matter how much has been poured into the glass - it has to go back.

If it's to check whether you like the wine or not, then are they implying that it's ok to request a different bottle of wine just because you don't like the first bottle ?, even though it was wine that you chose from the menu and there's nothing wrong with it (other than you don't like it) ?

I could understand if you had asked for a recommendation and it was not what you expected. For example, you'd asked for a dry white and it tasted like dessert wine.

So my question is; is the tasting to decide:

a) if there's something wrong with the wine , or

b) whether you like it or not.

If it's b, then is it acceptable to return a perfectly good bottle of wine just because you don't like it ?

For information, I never bother tasting the wine and usually ask them to just pour it (and yes I'm occasionally disappointed, but I can count on one hand the number of corked/bad bottles I've had - and I probably eat out around 75 - 100 times a year). I seem to be in the monority though, looking around me in a restaurant, most people seem to taste first then ask for it to be poured.