Yes a small number of people care and would want to know. The CD insert may be different (stripped down if the retail version is particularly elaborate) and the BMG "barcode" they put on the back of the inserts is always more obtrusive than the retail barcode. Picky, yes. But a certain percentage of music collectors tend to be that way. To me it's not worth the risk of getting your perfect feedback dinged over something so trivial, when a simple "Mfd by BMG Music Club" somewhere in your auction description should be good enough to CYA and will not scare away the masses.
I haven't noticed a difference in music quality (some have argued that jitter is potentially worse with music club CD's). I read an explanation once that most of the question of quality with music club product goes back to the days of vinyl, when the record club masters used for cutting the vinyl would degrade over the course of a manufacturing cycle and they wouldn't replace them often enough, so that the quality of what you got from the club would indeed be more variable than retail. Or something.