The problem is that you have common sense and you can't understand why someone would say cash only.
I say cash only on all my ads. I had a d-bag show up, like the game and make an offer. He was local, and he wanted to pay me with "bank draft check." You gotta ask yourself, why would someone who is local, and who has the cash, insist on paying with a check. The only reasons for this is to screw someone.
It's a common misconception that bank checks / money orders can't be canceled. All a certified check does is validate funds, they CAN be canceled.
So yah, I say cash only because it's not obvious to everyone. I would take a paypal from most people that don't give me the heebie-geebe's though...
Serious inquaries only means that you can talk them down, but usually not much. I've had some guy bug me twice now about a game I'm currently selling trying to talk me down almost 10% which I personally think is a bit much, but saying no all day long is cheap and easy. I think any offer is better than no offer.
Quoted from examiner:
Although once I was gonna offer 1500 skittles for a pin, but I read the ad closer and I saw they were insisting on "CASH ONLY"....so I guess it does work sometimes. I didn't waste their time.