I sold a car on BaT last year and all went very smoothly. Respectful reader comments/questions, and a fast-paying buyer (nice guy too.)
Of course, it helped that my car was realistically priced (reasonable reserve $) and was honestly represented, with nearly 100 photos/videos, docs, old photos, etc.
I worked with my BaT rep to make sure the description was detailed enough. It needed to be lengthy as there was a lot to cover. Their first draft of the description left out a bunch of pertinent info. But, the rep was easy to work with and quick to respond.
The selling price turned out to be pretty close to my estimate (a hair under, but close enough.)
I may have had an extraordinarily good experience, but I would do it again.