Henry
Autoexreginated
OK, an RBDM is a "Rat Bastard Dungeon Master." This is a GOOD thing. A "Really Bad Dungeon Master" doesn't even DESERVE an acronym. 
What's a bad Dungeon Master? The guy who holds up his hand and says, "THIS IS THE HAND OF PLOT, TELLING YOU THAT YOU CANNOT DO THAT ACTION." Takyris related this story, and even though this individual has a problem that I'm not denigrating, that was an example of a VERY bad DM.
Milder examples include people who run nothing but flavorless combats, people who offer no reward for great risk, and those who railroad to the point of where all you're doing is naming PCs who become bit characters in a grand forced narrative. Thankfully, I haven't run into many.

What's a bad Dungeon Master? The guy who holds up his hand and says, "THIS IS THE HAND OF PLOT, TELLING YOU THAT YOU CANNOT DO THAT ACTION." Takyris related this story, and even though this individual has a problem that I'm not denigrating, that was an example of a VERY bad DM.
Milder examples include people who run nothing but flavorless combats, people who offer no reward for great risk, and those who railroad to the point of where all you're doing is naming PCs who become bit characters in a grand forced narrative. Thankfully, I haven't run into many.