I do not know about others, but I personally had a good experience with "some" vendors, since they are genuine and sent genuine traffic. However, the numbers were small, but the traffic was genuine, as promised. And, I'm quite satisfied and I earned double what I spent.
Apart from this, you can go a little creative too. For example, you can by the indirect root. How to get traffic in your videos In addition, you can also try the pints promoted by Pinterest, I mean genuine forms that can generate traffic.
But, before trying something, at least investigate, because according to my experience, there is always a seller that is better than what he has found and thinks like a gem.
Research is extremely important in this game!