On the topic of what *kind* of calories, I'm with both mind-sets here. For ONE meal, it doesn't really make any difference. Key part ... one meal. So long as that "one meal" isn't every day, or even a few times a week. On the other hand, eat 1500 calories of chocolate, and 1500 calories of broccoli, and let me know if your body notices the difference. Obviously, I'm being facetious and extreme, but at some point, the kinds of calories absolutely do matter.
I read recently that most normal people eat anywhere between 21 and 35 meals a week. So, if you eat clean for 19/21, or 32/35, you're still running at a 90% success rate.
So yeah, don't fret too much about a single reward meal, but don't let them get out of hand. That goes for reward "snacks" too. This is a bad time of year around the jingle.household, as there's lots of little candies and things that showed up around the holidays. I still have some maple fudge, and Ghiradelli chocolates sitting around. So tempting.