Its the same wherever you advertise ... I had my VW Touareg on auto trader for £X and got lots of "I can collect it today for £half X " and other similar crap. I just deleted them although I did go back to a couple and said "to you its £2x" ... then you get the "I'll be round at 4pm to look at it" and then never show.
A mate of mine was flogging his Volvo and 2 guys showed up, one asked to see the MOT history so he went inside to get it and saw one of them squirting something around the engine bay as he came out again. They then said "you got an oil leak mate, we will give you £halfX". Turns out the even put some in the rad expansion tank.