Using things like that is fine by me. I'm not going to distribute it commercially, so it's probably fair use as you are getting creative with Sim clothing without making a negative impact on the original brand. In fact, it's free advertising for them, too.
We don't really have our own logo. It's just the Sims logo with text around it, but the plumbob is copyrighted so that's the best I can do! I've thought of trying to get something more professional but somehow losing the plumbob bothers me too much so it'll stay the way it is. I think that is the only point I'd make when using logos from anything commercial. You can't modify the original. It can be on a Sims shirt but you can't make changes to the way it looks. With what we use for the site, it's just the Sims logo with text nearby. The plumbob is unscathed. Anything like a costume is probably easier. it's not a trademarked logo and things like a "catwoman suit" change from time to time with he character so it's just a general look that is open to tweaking a bit.