Al raises some good points. Wine should only be rejected if it has gone bad. You might not like a wine because it is thin, rough, too tannic, the wrong color or too sweet, but those are not reasons to send the wine back, just reasons not to order it again. The most common wine flaw is when a wine is corked, that is it has a funky moldy smell like old damp newspapers that have been sitting in an attic too long. Wine that has been exposed to excessive heat may become “cooked” which is harder to describe, but in extreme cases the wine no longer tastes like wine (I remember one bottle that tasted like not very good beer). Either of these is a reason to send the bottle back.

It is perfectly normal for a restaurant to stock the most recent vintage of a wine when they have run out of the previous year. There is nothing underhanded about this except for the most expensive wines as most wineries that produce in volume try for consistency from year to year, both in taste and cost. Ideally, the wine list should be changed to reflect this but that doesn’t always happen in a timely manner. Restaurants do run out of wines, particularly more expensive ones that they may only have ordered a case or two of. However, for older or more expensive wines it is not at all unusual for different years to vary considerably it both quality and price. For example, a ’96 Napa Cabernet might be 20% more than a ’99 from the same vineyard. It is perfectly acceptable for the server to suggest a substitution, but this should be done with an unopened bottle and with the understanding that you can reject it and order a different wine.

Scratching the cork to see if it is crumbly or powdery makes as much sense as anything. There are a lot of opinions on what to do with the cork. What you are really trying to determine is whether the cork was doing the it’s job, that is protecting the wine from the air.