This is a very controversial subject. There are a lot of people who would put a dog down the first time it bit/nipped/snapped at someone, no questions asked.
The only way that I would put a dog to sleep because of aggression is if it came to the point where I didn't trust the dog at all. Meaning, if it became a frequent occurrence, if he injured someone enough to be life threatening, or in the rare case that it was unprovoked.
When I was little, we had a Chow Chow and a Shar Pei. The Chow frequently growled at me because I would crawl on her and pull her fur and whatnot. Then one day she bit a delivery guy and the shitstick neighbor lady almost had a pulmonary and long story short, my parents had to put her down. I don't remember her, but I still feel bad about it. The Shar Pei snapped at me a couple times too, so they gave him to a home with no kids. In the case of both dogs, their growling and snapping was my fault.
Case in point, dogs rarely attack without a reason and it's almost always the person's fault. Our second Shar Pei turned on my dad and actually drew blood, but we didn't put him down. It only happened once and it wasn't very serious. He was a good dog otherwise. That kind of thing is to be expected from Shar Pei, seeing as they were initially bred as fighting and guard dogs. All three of our Shar Pei had strong resource guarding instincts as well.
I grew up with food aggressive dogs, and I'm still alive. That's one thing I don't like about most shelters and rescues. They usually don't adopt out food aggressive dogs. And it's really not a major issue.
You know how you solve that problem?
You stay the hell away from them while they're eating. I would bite too if someone tried to take my Doritos away from me. I understand how they feel. I learned at a very young age that you don't bother dogs when they have food in front of them. Shelters should put regulations on them and only allow them to go to homes with no or older kids. Make the adopters sign an agreement that clearly states that they understand that the dog has resource guarding issues. I do not believe that it's the shelter's fault, either. I do not pity the moron that gets his fingers bitten off when he touches the dog's food. And if a dog bites a kid, it's the parents' fault for not teaching the kid any better. If a child is old enough to walk, it's old enough to understand not to bother the dog. Either that or feed the dog in a separate room and close the door.
Furthermore, if you tease a dog, you deserve to get bitten. Do not whine and cry like a baby when it happens because everyone with a decent head will know that it was your own fault.
I also hate it when people (mainly solicitors) carelessly walk right up to houses with BEWARE OF DOG signs. Do you know what that sign means? That is a clear warning to anyone who does not live in that household that there is a dog there that will attack a stranger if given half a chance. They're called guard dogs, and that's exactly what they do. I do not want to hear about boneheads that get bitten after they went and did something stupid.
So. Any thoughts?