Callie hates wet grass too. I'm in Omaha and it's really humid here, so we get wet grass nightly, awesome
At first, I just picked her up and plopped her into the grass, she took care of business right away and then bounced back to "dry land". Now she goes out there, but only to potty, no sniffing around when the grass is wet. She also balances on her front legs when she pees, its kind of funny she does this almost handstand yogaish type thing. It impresses me! She really hates the wet grass, but know when you gotta go you gotta go!