The blue ones? There is a learning curve to be sure, but depending on the area you are in, you can make bank on them. Within 100 miles of me they regularly get bonused from $50 to as high as $90 each. Even at $15 you can easily do 8 in a day. That's $120 without any gas or reimbursements. They are easy once you get used to it. Most of us make cheat sheets to make sure we don't forget anything.
What those people are thinking is that gas stations create a LOT of work for people who do them. There are tons of them and they get done multiple times a year. Of course, they aren't for people who are too lazy to put in a little initial effort.