I don't like to use treats as a reward for good behaviour or weight loss. Partly, it just seems wrong to me - "I've lost weight, now I can eat a piece of cake".
Partly, I don't like the idea of food as reward in general. I think it fosters and obsession with eating, which is already a big enough problem in Western society.
The way I do it is that I incorporate 'treats' into my diet. I make sure that I don't deny myself something tasty now an then, but I don't consider them treats per se - I make room for them in my daily/weekly plan, and that ensures that there is less urge to binge.
The term I really don't like is 'cheat' days or meals. You're not cheating - you are enjoying a meal that you will account for in your plan, ideally.
It is fine to eat somethign other than bark and berries once in a while - just don't let that one relaxed meal become a relaxed day, then two days, then a week, then you are sitting on the couch with a jumbo bucket of extra crispy...