I've done this, most memorably coming back from Jomtien. I didn't want to cram into a stuffed bus at the regular stop and I didn't want to face the walk from Second Rd. to my hotel. It was worth the 200 or 250 baht and, creep that I am, I especially liked seeing the uncomprehending looks on the porcine faces of a couple of Russians when the driver shooed them away from getting on.
More commonly, I did it a number of times with my BF in order to go somewhere not on the regular route.