midorijin
GUI real estate is precious. Dedicating two full size, non functional buttons to something that should be self evident (based on the filters you specified)... seems less than optimal. If you care if a scene has sex toy or passthrough support, that's what search filters are for.
The icons never go away either. They mask a portion of the tumbnail image and clutter the search results page, it just looks ugly.
Dedicating that space (on hover) to buttons with actual functionality, that makes more sense.
But if the community REALLY finds these icons useful, the best solution is something like you suggested - the ability to customize what icons/buttons appear on the thumbnail. Or at least a toggle option to 'Mark scenes with sex toy/ai support'. When checked, the icons will appear.