I have to admit that yes I have. Many times. Now a days, it's mostly cat litter and the dumpster doesn't have a sign on it. Not that that means I couldn't get in trouble for it though. My heart races a hundred miles an hour during those 5 minutes.
Few things are funnier than catching the person in the act. Depending on their attitudes when warned not to do again, I've even had them remove their trash versus my calling the police.
Years ago when I was moving, I had so much stuff to dump but the apt. dumpster was full......so I snuck over to a small business nearby to dump my stuff, and got caught!!!!!! they asked what the hell I was doing and I just took off!!!
embarrassing, right? I should have gone back after dark but didn't think of it at that time........oh well!!!!!!!
No, not only because it's illegal but also my household refuse is collected regularly and the Council's public skip-yards for bulkier waste are close enough to my home, and open for sufficiently long hours, to be reasonably convenient. (Though they now charge for you giving them certain types of waste, and put volume / time limits on material like building rubble.)
Garden waste is turned into compost for sale. Metals, of course, are sold to registered scrap-dealers. Not sure what they do with scrap timber.
Despite widespread official waste-sites we still have problems with fly-tippers, selfish morons who seem to delight in driving out into the countryside to abandon building rubble, old domestic appliances and the like to cause problems and expense for land-owners (mainly farmers), and offend everyone generally.