I’ve been thinking a bit about the common pushbutton switch such as the Carling 110/316 series. They’ve been the standard effects pedal switch for years, albeit some outfits use cheaper knockoffs, likely to their peril. The nice thing about such switches is the great feedback they provide, even if one has a really thick boot on. Another great feature is their non-teasable nature, ie the contacts operate on an overcenter mechanism, so chattering on opening or closing is near impossible. Likewise, they are self cleaning via contact wiping.
However, if someone flings a beer, or worse, someone puts a beer on an amp, (where it is guaranteed to tip over) and you get beer in the switch, the party is likely over.
This problem is somewhat mitigated by using a hinged cover plate over the switch such as in some Maestro pedals of years ago. Then again, hinged cover plates, whether custom extrusions as in the Moog, or plastic as in the FCB1010 serve to add extra cost. In addition, while deflecting most of the beer, ingress is still possible.
Capacitive sensing works wonders as far as providing a beer proof switch. Likewise, inductive, or even magnetic sensing can do well in the volume/wah pedal arena as far as beer proofing.
A big problem with capacitive sensing is providing feedback to the user. A LED status light while helpful is no where near as good as the massive tactile response one gets from a Carling 110/316. A possible solution to provide feedback in addition to an LED is a shaker solenoid, such that at actuation, the musicians foot would receive tactile confirmation.
Another problem is the issue of teasing, where in the over center action of a Carling 110/316 reigns, and capacitive sensing crashes and burns. Ie unlike most other apps, one cant use a long debounce time in a music application or you will aggravate the musician to no end. Adaptive tuning of the capacitive switch may or may not be an answer to this issue.
Lastly, there is the issue of musician preloading. Ie, its common practice for a musician to rest their foot on their pedal just prior to actuation. Again, adaptive tuning of the capacitive sensor may be an answer, although at this time, a mostly mechanical approach in addition to tuning on the fly seems more reasonable.