Duh.... call me dumb but what exactly is an incentive search?

If you look up in the dictionary what incentive means that pretty much explains it

incentive search= giving someone a reward or an incentive to search for you. Be it cash points anything like that

In other words dont send a paid email with an incentive of any kind to search

i have asked some search engines that they said ads in paid mail companies are allowed but should not tell readers what to search

that's why you see paid mails that say things like
"Please do not click unless you intend to search"
and
"Make a search, but you don't have to"