If I can't launder it, I dry clean. I admit I'm a bit of an over-launderer with my clothes.
All of my jackets and blazers are dark colors. A couple of dark shirts I own do get a sweat ring (thin, polyester satin material). But the blazer I own now is heavy enough cotton material it doesn't show a single thing. I just launder it when I can. It says dry clean, but sometimes I'm daring!