Personally, I'd avoid the 'free' pets.
Odds are the pet is ill. Even if it's not, if a person can't afford to buy a pet, so is looking for a 'free' bird, then how can they afford to keep a pet? I also have met several people over the years who won't get a vet for a 'free' animal, because they don't consider it's worth it...after all, it was free so has no intrinsic value. Why put money into it?
There's no guarantee either way of course...but I live by the adage 'if it sounds too good to be true, it likely is too good to be true'.
The other one that really bothers me are the ads by people asking for 'free' pets because they can't afford to buy one...again, if you can't afford to buy one, how can you afford to keep one?
I remember one ad begging for a kitten because the young 5-year old daughter really really 'needed' one. It had to be free of course, because they had no money...but it also had to be friendly, neutered and up to date on all it's shots. They would prefer if it came with a litter box and food too...but if it didn't that was okay.

Every parrot has a duty: To reduce the world to toothpicks.