The entire industry can tell you that the signal to nose ratio of most abuse reporting mailboxes is heavily skewed towards noise. If an operator has an abuse email anywhere, it will be run over with complaints from users who saw one of their IPs in a spam message header, or who saw something logged in their home router/firewall logs and WANTS YOU TO MAKE THESE ATTACKS STOP IMMEDIATELY.
not our experience. we have non-trivial research space, some of which does active probing, nothing hostile. we get a message or two a month. and we respond. tiny compared to the general level of spam and of the folk skimming whois data for email addys to try to sell or buy ipv4 space. as your experience is so unlike ours, should we suspect there is a skewed distribution? perhaps this research project will tell us. randy