I find that one of the best indicators of a scam is when you find yourself asking “is this a scam?”
When they turn up they won’t have cash, they’ll have some bank disaster story with a side order of “I’ve just driven all the way from London, give me a break here mate” and some alternative form of reversible payment they can use. You might want to have a couple of burly mate pop round for a brew coincidentally also, just in case their idea of payment is a bat.
Could be genuine of course, but I’d be tempted to stress that unless they turn up with actual money and nothing else they’ll be turned away.