My wife won't turn down a penny offered by anyone. She's money hungry.
My personal take on it is I invited them and I'm spending the same amount of money whether they go or not, so I don't expect anything. I do however appreciate it when someone offers up gas money and I generally don't turn it down if it's someone who got in a fair share of pulls. It does help, and I do make sure any money I get goes back in the gas tank and not lost in my wallet.