As mentioned in Using Korean transportation apps (Naver Maps, Kakao Maps), Kakao Maps often has very direct and honest reviews. Without reading the actual Korean review content, one can use the following heuristic to help find great places:
Step 1: Search by category.
Searching by fixed category helps avoid the app incorrectly understanding English search terms. In the example below, we search for restaurants (음식점).
Step 2: Filter by minimum 4 stars.
As mentioned, Kakao Maps reviews are often very direct, so this is a high bar.
Step 3: Focus on places with higher review counts.
If there are only 2 or 3 reviews, for example, it's hard to say if it deserves its rating (unless you read the Korean reviews).
Finding great places to go is an art, and this method is by no means perfect, but hopefully will help find hidden gems one would otherwise never stumble upon.