It is really that necessary an adspy tool?

[Dnurz]

I mean in some courses I have made they say that is not that necessary, that you can ask your affiliate manager for the best offers or spy manually and that can be enough

In others courses they say the best option is a spy tool because it would save you a lot of money finding good offers and not wasting money in the process

So considering spy tools are really expensive, I would like to know how profitable they really are, how much money they can save you and if can find good offers very quickly without