Luxury goods can only hint at socialeconomic status, not confirm or deny it. Some wealthy people do not care for designer handbags, some not wealthy people do care for designer handbags, and vice-versa. Some people do buy for perceived status but some do not, and most are probably a bit of both. It really depends on the person.
People who care about designer handbags are a set of people who can only be defined by their love of designer handbags. These people are rich and poor, educated and not, the only common thread is their love of designer handbags (and perhaps of handbags in general, though not always the case). Given this, who cares if someone buys a handbag on sale or at full price? Some people have to work harder, shop smarter for their designer bags, some do not. The common thread among these handbag lovers is their love of such handbags, not of "status" (of course some care about "status," but it's not all). So why shouldn't the ones who work harder or shop "smarter" (ie pursue sales) have them?
ITA.