I have a tackle tray full of DT06's and have yet to break the bill on a single one. I bang them off of rock, wood, cinderblocks, bricks, everything, and not once have I broken the bill on one. I have wore the bills down on a few to where the front edge of the lip is fairly close to the eylet, but they havent broken. Not sure if ya'll got a bad batch or what, but they have outlasted most of the bandits, bombers, and strike kings that I used. More importantly, they run true out of the box. For a little over a buck a piece, you basically stole them. An EXCELLENT crankbait that has proven itself to catch fish and will be around for a while.
As a rule of thumb, I dont smack my baits on the water to get weeds off period. Its a bad habit and could potentially scare fish in the area so I don't do it.
As Sam stated above, cast them to shallow areas (4-5 feet) with sandy bottoms and let them stir up the bottom. I usually reel in 3-4 turns of the handle on a 7.1, then pause for a split second and start again when running it across sandy bottoms. This has produced well for me. If you find rocky bottom, do the same but retrieve the with a slower turn of the handle to where you feel the lure just barely nicking off the rocky bottom. I generally dont like the crank to dig too hard into the rock, just contacting it enough to cause a deflection of the lures path.
Again, its a fantastic lure that you purchased dirt cheap. Dont hesitate to throw them anywhere, if you lose or break one it only cost you a hair over a dollar. Also, if you are fishing where the fish are, your gonna loose some lures so remember that its just part of the game. Best of Luck