It makes you feel overcharged even with the discount, the product must actually be junk
I don't feel that way. A 10% discount simply sweetens the deal for a commodity (clothing, furniture, etc) I could get at many other places. It's the cost of acquiring a new customer.
The whole reason I'm stopping to look around is because every price tag just got 10% lower.
Because they are throwing money around which means they either have ridiculous margins or are just desperate for cash.