*Especially* cool maps like duck, kurczak and trololo.
Well, not really. Trololo can stay because it's very direct about what it is. Duck and the other 4x4 maps are trololo with a different texture anyway so who cares.
Same for speedmetal. All the clones are basically the same thing with minor variations so just tell people to play the original instead.
That would be the nazi solution. The milder solution is to let existing shitmaps be but filter out the future ones.