I was ruminating on your dumpster diving talents and the recent Bear steals dumpster GIF, when I wondered if perhaps it was feasible to build and deploy some sort of dumpster monitoring system.

Essentially: trigger a few minutes of video recording when a sensor indicated that the dumpster lid was being opened. Pushing the video to the net would be wonderful, but not necessary. You could regularly make your rounds, perhaps swapping out old memory cards for new on each dumpster, or connecting a small mobile device to pull the new video data from each unit. You could look at the video recordings and decide which dumpsters to dive, and even determine dumping patterns (for example, perhaps a local metalworking company dumps at 10AM every Wednesday, but a local burrito shop dumps at 12PM every day, so you want to dive that unit at 10:30AM on Wednesday).

There are some legalities involved, but you may be able to overcome them with creative but legal sensor/camera mounting strategies. The sensing and monitoring equipment is cheap enough these days that you could build this largely with discarded or very inexpensive equipment.