Free royalty free stuff is slightly sketch. But so long as it is from a reliable source, you could probably send the legal issues to the site owner. I would suggest you check out the producers choice and pay money for a pro sample pack. It really does make the difference, I've gone through a lot of samples. And It is always better when you keep 85% of the samples you come across.
Exactly, you gotta be careful with sample company's. Make sure they're reputable because a lot of stuff gets recycled around and a lot of sites are selling stuff they don't even have the rights for. A general rule if thumb for anything internet related, if it seems sketchy, it is.
Well if it is a somewhat legit business, with a name or organization you can hold accountable. And use legit ways to provide content, I would say they are trustworthy.