How to know if someone is C# ninja?
when you read his code you’ll find a lot of Foo<T> , TModel, TKey and a lot of reflection

Reflection is awesome when used properly.

@MrCSharp but should be used sparingly though. Adds a bit of unnecessary overhead

Use of generics is like most features only as good as how you use it :)

And I had a colleague that very visibly proved that knowing a lot of advanced features and using them do not make you a good developer :/

He knew generics, lamba, reflection, the new pattern matching switch and similar but the code still was copy paste mess of over engineering with no regard for loops in loops, they where just more hidden in all features.

But when you see the features used in a good way that actually reduces the complexity or saves large amounts of code, then you know the dev understands the concept and you should pay attention :)

If by ninja you mean deadly and being unpredictable and hard to understand than yeah, you're probably right.
(Actually most of these things are fine when not abused)

@Voxera soo agree with this