In general, I just shake my head at complainers. I deal with it at my job where I have to actually interact with them and engage their complaints, so when Im kicking back I usually choose to abstain from it, because quite frankly, it gets old dealing with it. When I see people embarrass themselves in person by complaining over petty things, I generally handle it the same way as well. Because this person is already creating a scene and being obnoxious about something trivial, like at a gas station for example barking at the Indian guy who didnt go fast enough for their liking or whatever. Why would I want to get myself involved when all I want is a pack of gum?
That said, when you behave like that, not saying anyone does but when someone does, they are pretty much opening yourself up to whatever comments happen to come. What you call "complaining about complainers" I call I dunno, maybe its karma. Negative energy breeds negative energy.
If you focus on positive things you'll generally recieve positive things. This isnt the mystical secret mumbo jumbo people try to make it out to be, its an actual working philosophy. Silly to apply to something as trivial as this, but its like kung fu, it can be applied to anything really.
If you spend a lot of energy complaining about something, its not going to net you anything good, I can promise you. What other people say about it is just the tiniest manifestation of that. Its bound to come, but probably the least of your worries.