Now ya got it right!! If you want to be angry with someone make it the irresponsible owners (in most cases) that don't understand the responsibilities involved with being a pet owner and don't spay/neuter if responsible breeding isn't in the future.
My local SPCA is very much supported by the community and is building a new facility with a dog park, agility area, and wonderful facilities for the animals and it is a no kill facility. They work closely with the animal control facility and take in those dogs that are not claimed. Right now, they are at full capacity to the point that supporters are taking home dogs to foster until adoption process can be completed.
If you would just give your local ASPCA a chance I'm sure they would welcome your volunteerism. They may have had a bad day with an unusual day of drop-offs and were stressed out to the max. Give it a shot and if it doesn't work out then tell them and leave.
Good luck with the results!
Labmomma X 2