*stands up*My name is Gold Roger and I'm a killer DM.
Now, it's not that I TPK my group regularly (one TPK so far). However, we do have a high mortality rate. I'm a tactician player and as DM will always play a bit to my own preferences. I simply think an easy fight is dull (I often have to hold myself back because I DM for a bunch of buttkickers).
I don't pull any punches, try to play opponents to their intelligence and have the world react according to their action, which can end quite badly for the PC's.
For example currently two are bound up on deck of a smuggler ship that was to take them into another town. The crew currently searches the ship for the other two, who where clever enough to find themselfes a hiding place to sleep. One of those currently has no weapon, because she drunk herself into a stupor in the shady part of a shady town and was robbed in consequence.
That's what happens when a group with the reputation of unscrupellous killers (didn't get the nickname "The Slayers" for nothing) bullies a ship of pirates and smugglers to take them without payment, then pisses of the crew even further and then all go to sleep without even posting a guard.
I simply don't believ in pulling punches. However, in a hopeless situation it always help to relax for a moment. Often there's a non cheesy, fun and logical out lurking in some corner of your mind you just don't get at the moment.
It also helps to not throw a situation at the PC's and not thinking of any outs beforehand, simply relying on "they'll figure something out". Always have two or more outs at the ready and point little clues to each. If they come up with some of those, you don't have improvise it. If they figure out something else, great! And if they still can't find a way out, give one to them, but not before someone died (again, I'm all for not pulling punches).