I did this for my recent automobile purchase. It's very convenient from my perspective to simply write a check and hand it to them.
2. If they charge you extra for using a credit card, they're breaking even
3. If they _don't_ charge you extra for using a credit card, they're paying 3% of the purchase cost to the credit card company (so, $1,000+)
So yes, it's a dick move to pay via credit card for any purchase in the thousands of dollars, if you have the option to pay by check or debit card. I always offer to pay by check if I know the money for the CC will come out of their pocket.