First of all, your headline is misleading. The article says: "Nearly 90% of users we surveyed were either unhappy or neutral when it came to mobile advertising offers." Last I checked, neutral != dissatisfied. (Granted, the actual number if you look at the bar chart is still a whopping 70%)
But if you look at the other charts, it shows that users were somewhat more satisfied with the other, non-mobile based offers. If the entire industry was based on scamming people, customers would report 100% dissatisfaction across the board.
Plus, you can avoid offers entirely and just opt to pay for the virtual currency directly. Perhaps you think such users are foolish, but they're certainly not getting scammed.
None of this adds up to "The entire social gaming business is unethical and evil", as the TechCrunch article would have you believe.