It was an interesting question, first time someone ever asked me this!
My way of dealing with slippery folks, is create a scrambly handfight, close the distance knowing they will slip out, but i use that moment as an opening. Why?
When you know you can slip out of grips, you are not as sharp and focus on techniques. Typically sweaty grapplers overreact and get a bit more complacent.
Thats my opening!