Everyone has their own take on regifting - some people won't do it, some people think it's totally fair game.
Do it thoughtfully and you'll probably never get caught.
Sometimes though, people fail in this respect and regift to the person who actually bought them the gift in the first place
Or the regifter gives someone something that is completely and obviously a regift - like gifting a fondue set to a toddler.
Got any real life 'regifting gone wrong' stories? My MIL once regifted a body shop soap to me, but she gave me other things too so I wasn't at all bothered