So many are "Which of the following places have you visited recently?" followed by a list of stores I've either been looking up or was navigating near.
Probably 98% of the time the correct answer is "none of the above" so that's what I pick and I get my 5-10cents. Occasionally I can tell that it's a survey that someone commissioned (asking about how likely you are to vote in some primary, etc) and I do tend to answer those as well.
Overall in the time I've had the app I've collected $60.19 (just checked history). Granted, this is from two years of use but it's good pocket change for Play Store purchases (hey, that $1.49 icon pack or watch face I wouldn't normally bother with? Purchase.)
I guess on some level I understand that like radio or free alt-weeklies, they sell access to eyeballs and earholes in order to fund the services I actually make use of. If they're gonna analyze my usage to try to determine which things are relevant and cut down on spam and wasted ad expenditures, I might as well make a few bucks from it in the process.
And as you say, sometimes I get one that I don't want to answer and it's pretty clearly laid out so I can decline.