To the original question. Look at it, to see if the colour is "right" (not brown for example). Then smelling that the wine is ok (no taint or off-smells) is the important piece. Actually tasting it should just be confirmation of what you see and smell, and I frequently don't really see the need for that step.

If there is something wrong with it, no need to make a fuss, just politely explain the problem and ask for a different bottle.

Problem is, many people don't have the confidence to distinguish between not liking it because the wine is tainted and not liking it because it's just not their style...so they accept a faulty wine because the experts rate it

Which brings up another peeve. Just because an expert rates a wine high does not mean you should like it...taste is personal so just stick with what you like for the price you are willing to pay.