Avoid them as they offer rubbish money for your caravan. I got the best genuine reponses to my ads on the pratical caravan forum as you can also show the layout of the caravan. Also eBay classifieds is good as it only costs £12 per month and you don't have the hassle with peopel bidding etc. Never fall for the "I can't view the caravan as I am elsewhere, but will pay you £10,000 for your £6000 caravan. Sed the the difference back to me" scam!
We insisted on a cash payment and refused bank drafts as even a bank draft can be recalled . Same applies to checques.