I don't know, but I would be willing to try - the one time I returned something to a local Target store (something I'd ordered online) - the staff at the returns/customer service counter were excellent - I had no problem returning my online ordered item, and I did *not* happen to have my receipt on hand. They were able to just scan it at a terminal and refund the $ to my credit card.
I think it's worth trying to return it. Definitely bring the tags - in my experience, the customer service person was able to scan the tag (since I didn't have my receipt either) and process the return without any problems. I was so pleased with the 'ease of return' process when I went to return something I'd ordered online, that I ended up buying a bunch more stuff since I was in the store anyway.
While I haven't returned something to Target that's already been worn, I *have* returned something I'd ordered online without a receipt - and the tags on the item were 'enough' to process the return. No hassles and no problem.