All one has to do is contrast FR to DU. On the former you’ll see some biting wit/humor on almost every thread. On the latter, none — deadly serious (and profanity laced) all the time. Quite revealing.
I've noticed that, as well.
I don't frequent the DUmp, but every now and then an LGF link will point out something outrageous, and I venture in.
The whole place has NO humor, NO happiness, NO joy. There is NOTHING comparable to the Official Friday Silliness Thread. What passes for humor is mostly Bush-bashing.
Of course, if I hated my life, my country, and my job, I might have no humor as well.