Valve Lash Adjustment

So my engine builder took the pan off and said the oil looks horrible and thinks it is the root cause of the lifter problems.
Before these lifters started giving me problems I had a carb bowl flooding and he thinks that's what ruined the oil.
The gas washed the carbon into the oil which diluted and soiled the oil.....I had no idea this was possible but he builds the engine pretty loose and I am sure this has a lot to do with why so much gas went into the oil.
Hopefully there is not any major damage caused from running the engine with dirty oil. The engine only has 1500 miles on it. What a mess!