The term "hit or miss" / "hit and miss" is used when describing things which might be successful or might not be successful or are disorganized and have no predictable results.
Example:
1.
A: "How was the food at that new Italian restaurant down the street?"
B: "It was kind of hit or miss. The appetizers were excellent, but the main dish wasn't great. I should've gone to Monteverde on Madison Street."
2.
A: "I don't trust this car dealership. I heard buying a new car here can be kind of hit and miss."