Are those black tank cleaning wands worth it?

I tried one, hated it. Best method I've found it using tank additives. You add it to the tank after flushing, then use the tank as normal. When full you dump as normal. The enzymes in the additive will dissolve all solids in the tank allowing for a clean dump. When I plan to not use the rig for awhile I add appx. 20 gallons of water to the tank after dumping, take it for a short drive and then dump again. While the wand may have worked, I hated dragging a hose thru the rig or in the window. Use the additives and chances are good your sensors will read correct. I don't use the additives every time...when we were full-timing I did it once a month or every other month. The main thing was to not wait too long and things had a chance to really take a hold in the tank. I never dump the tank until the toilet burps so I know it's full. And use plenty of water when flushing, you can't use too much water.