California is Ground Zero for creative petition gathering techniques. Reading about Wisconsin Republicans petition fraud attempts fills me with a perverse regional pride.
At least half of all California petition initiatives are funded by industries seeking special interest legislation they couldn't get through the legitimate bribing of politicians. A classic example of this is 1994 when the tobacco industry qualified a petition for the ballot to regulate smoking by eliminating existing regulations. It only qualified because the paid signature gatherers told voters the petitions would "regulate" smoking rather than deregulate smoking (they lied). The initiative lost in the election because the lie could only last so long.
Paid signature gatherers are decidedly amoral. A common practice is for one side to try to out bid the other. If they are paying $1 a signature I'll pay $2 a signature for another measure. The price has gotten as high as $20 per name. They will just a readily carry a petition against hate crimes or one requiring interment of Jews.
Forgery and other fraud isn't common because it is too easy to get legitimate signatures. But, at these prices it does happen and is almost never caught.
The paid gatherers can be aggressive and will often intimidate volunteer gatherers to leave prime spots. Think of paid signature gathering as legalized panhandling.