Spamcop may be annoying, but it is a lifesaver to me. I am a Spamcop subscriber and all my mail gets filtered through Spamcop. Their blocklist is dynamic so if a spam source stops spamming, it falls off the list.
There are two ways the DH server can get on the list. One is if someone on DH is really spamming, in which case the listing is correct. The other is if a Spamcop user forwards their DH mail to Spamcop, fails to register the DH server as a "known mailhost", and then carelessly reports a forwarded message as spam. This is similar to the AOL problem except that Spamcop has a robust mechanism to find the actual spam source further down the header chain.
Spamcop, unlike some blocklist providers, maintains a responsive staff and works with hosting services and ISPs to resolve issues quickly. Yes, it is a pain when one of the servers that forward mail to me gets on the list for a while, but I'd rather that then get so much more spam.
And, FWIW, the DH server is off the list now.
188.8.131.52 not listed in bl.spamcop.net