A very very high negative count slightly favors the player. It is rare to get to such a count and you would have to play through a ton of negative counts that favor the house much more to get to that rare and very tiny advantage. And then you would have to know the specialized strategy to use, would involve hitting a lot of 13, 14, 15, 16, even 17's vs dealer break cards. You are far better off just not playing any of those negative counts like -2, -3 or higher.
But yes, in answer to your question, there are things that can be done to gain an advantage once you identify such a situation. If you remember, my sharing this incident of casino cheating, which I though was me warning other players, resulted in a team of AP's that had also discovered this situation and were taking advantage of it, being quite angry with me. I got a couple emails calling me some unpleasant names. I think most of that group has come to understand that I made a mistake. I thought I was warning players and it ended their play. But there is one guy that has been very slow to forgive and forget...let's just say.