I have a website with some portion of traffic that is valuable/converts well. (For example I know that some of my visitors convert for paid service of monthly subscription of $10 - I know it because I use affiliate banners from time to time)
But I also have very bad kind of traffic probably originating from botnet I think it is responsible for that 4 - 8% of invalid activity I'm getting each month.

my questions:

1) Does it mean I'm not getting full price per click from legit visitor when he clicks and makes purchase/subscription?
2) If I try to filter that bad kind of traffic from showing adsense ads how long should I wait before making any conclusion?