If by trust you mean not ending up with a token that’s worthless, if at all, then I would basically only trust those that pay in BTC (see Overview of Bitcointalk Signature-Ad Campaigns [Last update: 14-Dec-2018]).

Now obviously those are tough campaigns to get into, and you need to be at least a Member aside from a decent poster, so in the mean time, you will have to scout around the Bounty thread in the Altcoin section and roll the dice there.
 
The best piece of advice I can give you is that, whichever campaign you enrol in, take the posting seriously and create content that, while not necessarily extraordinary, it is not down to qualify as spam. One’s imprint is the sum of his/her posts, and that is always on the profile’s history for others to view.