I think you're being a tad petty.
I would have just said, "sorry i'm too busy"...rather than 'see you next spring'. But I totally see why you did it.
You're obviously a really nice guy, took this one on face value, let your guard down a bit, and it's come back and bit you on the arse!
Most of the time we get it right, occasionally we get it wrong! Me also!
As for first cleans, I charge a bit more, depending on how long I think it will take. If the customer doesn't understand that, then I don't want them.
When I started out, I had bills to pay, mouths to feed, I cleaned anything for a fair price (if I could get it). If not I bloody cleaned it anyway. When you're starting out, some money is better than none.
Hindsight is wonderful thing, and we can all be 'billy big b******s' looking back, but now 'i've set my stall out' and i'm happy with it.
The trick is; not to worry about the few customers that cause you arse ache, but learn how to replace them, with hopefully better customers!