Depends what guarantee they are going to give I suppose, ie if the car arrives and it isn't as described you shouldn't be liable to pay for it and should have your deposit returned.

If I was buying anything for 10's of thousands then I'd definitely have an independent inspection done by the AA or similar regardless of where I was buying it from. Money well spent for piece of mind.

People order brand new cars which they haven't sat in and drove and still get loads if issues.