Also, keep an eye on the paint near where the clips engage the roof. On my old Mazda 6, I noticed one spot where the clip had rubbed against the paint and wore down to the primer. Couldn't see it until I took the deflector off. Another tip: Every once in a while take a look and make sure the drain slots at the corners are not plugged. On mine, leaves and other tree-related debris or ice buildup in winter would block those drain holes which caused other junk to build up in there.
My recommendation based on my experience with these Mazda deflectors is to take it completely off and clean and wax under there at least once a year minimum. Twice or more preferred. Driving rain and snow and ice in the winter can, and almost certainly will, drive dirt under the rubber seal on these. These things do move/bounce slightly under road vibration and aerodynamic loads which can create an abrasion action.
