What I have notice is that signature campaign. Most pay with their token while only few ones pay with Bitcoin or other Altcoin like ETH. Someone need to be careful not to waste time on project that will not pay. Because I have experience something like that. I have work in a project for three months before discovery that the project is not going to pay us. I regret why joining signature on that particular project. Wasted my time and effort so, someone needs to be very careful on the project he need to involve signature campaign.
most signature campaigns arent scam as long as the manager that manages it is well known like for example if the campaign is managed by yahoo, then that campaign is probably legit and would pay you. the only campaign that you need to avoid is mostly bounty ico campaign or altcoin campaigns because most them are only managed by a newbie account. Looking for an escrow is also a sure way to ensure that your participated campaign will pay you.