Going on the sellers honesty!!!
Many on here will support the view you should never buy a boat without seeing it yourself or getting someone independent, preferably qualified to look at it before purchase. You could get a large headache and an empty wallet if you don't. It's not like a car where if it has an MOT from the last month or so, is hpi clear and has Full service history, you can guage its condition.
It may look nice, but as many have found, decks can be rotten from the underneath, hull cracked and painted over, the list goes on!
There are many friendly qualified/semi qualified people on here that will help, some may or may not charge, depending on distance to travel, extent to which you want help.