How to talk to parents about their kids (when you don't have kids)

 I had two experiences recently with good and bad examples of how to talk to parents about their kids.

The bad:

I was recently on vacation with my family at the east coast. While there, we visited a convenience store called WaWa (I had never heard of this place before, but apparently it's a big deal in Pennsylvania). We had promised our kids some ice cream, so we let them choose the ice cream they wanted and then we approached the checkout counter. I needed to do some crowd control on the kids because they all tried to put their ice cream on the counter at once, but I managed this fine without any commotion. However, the guy doing the checkout (who was a teenager, likely without much experience with kids) jokingly said "Little monsters!"

After I completed the transaction, he offered another joke: "We've also got aspirin on sale if you need it!"

I'm not sure why this guy said this, I guess the idea was "Kids are annoying, so I'll make small talk about how kids are such a pain in the neck!"

While I concede that raising kids can be tough sometimes, most of the time I think they're pretty great. And they weren't particularly unmanageable in this instance, they just needed a little organizing.

The good:

On our return home, a guy at the airport was checking our boarding passes and IDs. We were about to tell our kids to take their kindles out of their backpacks, but my 8-year-old had already done it. The guy said, "Wow, you did that already? Everybody should be like you!"

This was a much better interaction than the first example because the guy said something positive about our kids rather than something negative.

In conclusion: 

If you don't have kids, and you want to talk with kids or talk to parents about their kids, it's generally good idea to be positive and assume they are good, rather than assume they are the worst and talk about how bad they are. That's punching down. Don't punch down.