I've had great experience with CL in the last few years I've been using it, mostly to sell stuff. Sold $1000s worth of furniture a while back (~4 years old listed at about 40-60% of what I've paid originally), college textbooks were usually snapped within a few days after being posted, miscellaneous stuff from around the house, old Sony 27" CRT got snapped in 3 days for $50, etc. Just ignore the lowballers and filter out folks based on how they write to you. Googling their email/alias helps too.
EDIT: Oh yeah, sold a junk car on CL for $1400 while getting measly offers for $200-300 from local junk car companies.