I am a newbie (just posted my intro...) but wanted to chime in on this thread. I am SO glad to see that I'm not the only "serial returner" here. Part of why I shop so much at Nordstrom is their excellent return policy. I just returned 8 items last week (all unworn, of course, but up to 3 months old) and am so glad I did it. I think that it can be really hard to know whether or not something will work just based upon a fitting room impression (even harder with online orders).
I started to make a policy for myself re: shopping (since I still do too much of it). If I haven't worn something within a month, I will return it. A few items have escaped that window, but I've found that it's generally a good policy. We should want to wear what we buy RIGHT AWAY. If we don't, it probably wasn't a good purchase. Buying sale items at the end of a season for next year is usually not a good thing to do. I have rarely been happy with those items by the time the next year rolls around!
It's better to return lots of things than to have a bunch of unworn clothing with tags on them (or things worn just once or twice) in our closets. Nordie's hasn't banned me yet, and hopefully they never will!
