The last two cars I sold were via eBay and Facebook Marketplace respectively.
The eBay one was listed as spares or repair with an honest listing and a photo of the MOT failure sheet(s). The winning bidder turned up with his idiot father who tried to haggle me down. In the end I threw in a spare set of alloys (probably worth £100, if I’d ever got round to selling them), just to get them to take it away.
The Facebook one got a couple of nibbles on the day it was listed, and sold that day for £100 less than asking (and £200 more than I was expecting).
Appreciate that this isn’t a statistically significant sample size (and there are plenty of people with the polar opposite experience), but any harm in advertising on both??