I haven't sold anything on eBay in probably two years because they are (or can be and have been) down-right horrible to sellers. Imagine having your entire Paypal account embargoed for a month because some guy complained about shipping costs. And this after having fifteen opportunities to NOT bid, each of which --and the listing-- clearly disclosed shipping costs.
On CL you get back to a truer buyer-seller relationship. If you don't have social problems (meaning you actually like engaging with people in person) CL is fantastic. I like shaking someone's hand after closing a win-win deal.
Yes, the CL site sucks. Obviously utility trumps design by a longshot. I love nice design but I always remind myself of CL when stressing over "pixel perfect design" (a tendency I have). people don't use a service because they are in awe of the design, they use it because of what they get out of it.