In the review menu under "actual services provided," they have "sex:" yes or no; "massage:" with a drop down menu, (no, clothed, topless, privates to privates, etc), "blowjob:" with a drop down menu (no, with condom, without condom, etc). They could add "handjob:" yes or no.
Then if you look at a review that says sex-no, blowjob-no, handjob-no, you don't have to look any farther into the review. It should be easy enough to add one line item to the existing review menu, that is still in line with the rest of the menu, rather than adding a "DIY" checkbox.