). Although they still host a significant amount of crap, this particular range now looks almost clean and does have quite a few legitimate (mostly Russian) customers on it.
I ran an analysis on 1672 sites [csv] in this range and only two were tagged as malicious by Google and none by SURBL, which is actually less than I would expect on a sample of this size. I note that many sites have reputational problems at WOT which seem to be because of an expired Spamhaus listing (see this example).
If you've blocked this /20 then I suggest that it is reasonably safe to unblock, although I would regard other DINETHOSTING ranges with caution.