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The Wizard of Id is a legacy comic strip that, like most of them, was much better in its early years. Originally by Johnny Hart and Brant Parker, it's now written and drawn by Mason Mastroianni, Hart's grandson. Mason does an admirable job, especially since he also writes and draws B.C., the other strip Hart created. However, these earlier strips just feel more fresh and fun, at least from an artistic perspective (I think that joke was old and tired even in the 60s).
It's difficult in a written medium to convey if singing is good or bad, but I think Troob's unimpressed expression in the penultimate panel says enough. The drunkards don't seem to happy about it either, but I don't think they can be trusted to know a good performance when they hear it.