If an app gives me spammy promotional notifications, it either A) gets uninstalled (if I don't particularly care about the app), B) gets a 1-star review with a clear comment about the notifications, or C) all of the above.

The app I use to pay for parking spots suddenly gave me a notification once, apparently to try and get me to park my car more often or something. I gave it a one-star review, never saw one of those notifications again :-) (Which reminds me, I should revise that review.)