Should I label ByRef parameters in .net functions?

I am a constant advocate for explicit naming, so a constant naming pattern I use in methods is the words set/get in variable names for instance:

GetCarFromList(List<Car> carsToGetCarFrom, int idOfCarToGet);
SetCarState(Car carToSetStateFor, CarState stateToSetCarTo);

Under this kind of explicitness, I think I have avoided hungarian notation while still managing to make all aspects of the variables purpose explicit.

Personally I don't like the pattern of TryParse and avoid implementing them myself, I rather return null so that the consumer can use ?? when possible and avoid the ugliness of an if, especially when the use of TryParse is often in the middle of a method which makes it uglier to put the if and nest some guard logic which wouldn't be so bad at the top of the method.

Now, back to your question, I would think of maybe a naming like:

TryGetCat(ByRef catToSendOut as Cat) as Boolean

This feels less like hungarian notation to me and more like simple explicitness.

Hungarian notation is bad, not because you are putting information in the name, but because it is redundant information at best, and misleading at worst.

Which is why you should avoid this naming convention.

Your TryGetBlah is already your naming convention, blahOut is thus redundant. What it does is introduce a chance for it to be incorrect if you refactor a particular TryGet (unlikely, but possible, for instance if you wanted to pass in the current value and return a new one).

So, the TryGet pattern is not a problem, but the naming convention should be avoided.