I've had /23s and /22s listed as dynamic incorrectly, and anti-spam organizations wouldn't take them off even when they were either SWIPd through to my company, or were in my ASN.<p>Getting off the lists is an enormous pain in the ass.  They make absurd demands, like changing the rDNS on every single IP in the block to contain the word static.... as though breaking rDNS is a good idea.