That's also a good point. I'm fairly sure that Untappd once posted a "Slow Down, Buddy" screen when I'd checked in to 6 different beers within half an hour.
In my defence, I was at a beer festival and drinking thirds (which is the best way to sample beer). Nevertheless, it was a salutatory reminder that the app was making at least a token effort not to kill me.
They've recently redesigned their "badge" system so it no longer encourages risky behaviour. Rather than saying "You need just two more different cider checkins to get the badge" it says "We'll tell you when you've reached Cider Provider Level 3". That way you're not thinking "I've had enough - but I really want this badge!"