We just got back last week. The snacks are SOMETIMES marked on the menu but not always. The CS meal items are just generally all the "meals" plus a drink and dessert. I always asked the CM before doing the whole order, however, because I didn't want to have a problem.
Here are some cases where they were NOT marked and the only way I found out was by asking:
At Seasons in Epcot, DH got a salad, and the CM told us he could also get a side with that. Also at Seasons, kids were limited in their dessert to a cookie, brownie, or worms in dirt; nothing was noted on the menu about this, however. At Seasons we were allowed any dessert as a snack item, but again, this was not marked.
At the Boulangerie in France, you're allowed only a regular size drink as a snack. None of the pastries count. Nothing is marked on the menu (not even the drink).
At my resort (the Polynesian) in the CS place, many snack items were labeled, but many were not. Also, the specifics about desserts (you can generally get fresh fruit instead) or breakfast (just one item and one drink for a CS credit if you're using them for breakfasts) you'll often find you need to ask about.
I also found different policies depending on the location. At the Polynesian, for breakfast, you could get one muffin and a drink to count as a CS credit. On the other hand, in MK's bakery on Main Street, you'd get 2 pastries and a drink for a CS credit.
At TS, I usually would ask. At most places, you'll get the appetizer/entree/dessert/beverage. But at 'Ohana, they'll also let you get a beverage (I had iced tea, the kids had milk) AND a virgin daquiri or pina colada (the kids too). Our server asked if we were on the
DDP and then volunteered that information to us. So it pays to ask because otherwise, we would have just ordered the iced tea and milk.