Almost all of those things are a scam. I have round 4K credits owed from when I first started playing and thought it would be a good idea to get credits.
99% of them are pure BS and nothing more than either an entry point for loading malware n other *** on your computer or they're data-mining. Either way, you'll be lucky to get anything.
The surveys, when they're around can be okay, if you can qualify. I don't really get many of them that work anymore. Guess it depends on where you live as well.
Trail Pay and the Sonic asshats etc... just scams.