i buy most of my clothes used. i and for a long time i have divided used clothes stores into 3 categories: thrift, vintage boutique, and upscale re-sale.
thrift stores are cheap with a wide range of merchandise (e.g. st. vincent de paul). vintage boutiques are more expensive - they are basically charging you for picking out clothes that are popular now and in decent shape. if you have time and your own sense of style, thrifting is more fun. if you're in a hurry and want something that's pretty standard vintage (cowboy shirt, old levi's, etc.), then a vintage boutique can save you time because you know there will be several to choose from.
i have yet to find a thrift store in seattle that i think is as good as some in the bay area.
as far as vintage boutiques go, red light's pretty good, but not that great. i like the one in the u-district better than the one in capital hill. more of a vintage shop than say buffalo exchange, which focuses more on current styles/items. i don't like the amount of new clothing they sell, which has been increasing. i think this jacks up the price of their vintage stuff and changes the kind of staff they have (and thus their vintage knowledge). but, it seems to be the trend in seattle for vintage boutiques to carry new stuff now -- even goodwill does it some now.
i've worked in both thrift and vintage boutique stores. to the people who complained about bag checking -- hello -- people steal a lot from used stores (and worse). once the tag is off, it's impossible to prove they took it from the store, since they could have also owned the same used item.