How to tell if a rescue is legit?

I always ask to see their 401C3 or 501c3 papers, if it's a new rescue that I haven't dealt with in the past.

ETA: charitynavigator.com is a great website that rates different organizations. Not every organization is on there though.

 Call Animal Control in the county where they're located, check with the state vet's office regarding regulations for rescues in your state, contact animal shelters where they are, find out if they place out to them or if they've dealt with them and possibly check for breed organizations if they are breed-specific.  The other thing is to physically go to where they are and see the conditions the animals are kept in, even if they require a home visit, it's like you're doing one of your own to see how THEY keep the animals as well.  I know alot of rescues use foster homes and that would be inconvenient, but I had a bad experience and I won't get a dog again without seeing where it's been living and THOROUGHLY checking out it's history.

Just my .01 

Some good ideas, thanks.  :)

Edit:  Oh, one more question...does being affiliated with Petfinder mean anything at all, or can just any rescue sign up who wants to?  I don`t see anything on Petfinder`s site that states anything either way.

GypsyNBeau

Some good ideas, thanks.  :)

Edit:  Oh, one more question...does being affiliated with Petfinder mean anything at all, or can just any rescue sign up who wants to?  I don`t see anything on Petfinder`s site that states anything either way.

No, just being on Petfinder isn't necessarily a guarantee of a good or reputable rescue.  There are some truly lousy rescues (All Creatures Great and Small in NC) on Petfinder and some truly great ones who aren't.  IMHO, the best way to gain information is to stay local and contact as many local people who are in contact with dogs (if that's what you're adopting) and find out the local buzz.  You can do that long distance but it's much more difficult.  Ask the rescue who vets their dogs, then contact that vet, you'd be surprised what they will sometimes share or that rescues will lie and claim certain vets treated a dog because they assume you won't check.  We have pet stores here claiming local vets are the treating vet for their puppy mill puppies and when contacted, the vets are outraged they're being used as references and their only contact with those puppies are when unfortunate buyers bring their purchases in for treatment when they inevitably get sick.

Couple more thoughts.  If it is a registered rescue, some states perform inspections of the facilities and those inspection reports are available thru the state vets website sometimes (that's how I found out terrible things about ACG&S), that can be a source.  In Virginia, a rescue must report all of their fosters to the state vets office.  The state vet doesn't inspect the fosters, but they do have a list of the fosters and all fosters are required to be registered.  That would show that the rescue is following the law and being accountable and operating appropriately.  Call boarding facilities, vets, groomers, training places.  Lots of dog centered places will know LOTS about the local buzz on a particular rescue/group.