[cs702]

mattkirman: nothing happened to the owners of those printers, because I didn't run nmap with the "--allports" option. As the man page explains, by default nmap doesn't send anything to port 9100 precisely to avoid running into this issue:

  --allports (Don't exclude any ports from version detection).
      By default, Nmap version detection skips TCP port 9100 because some
      printers simply print anything sent to that port, leading to dozens
      of pages of HTTP GET requests, binary SSL session requests, etc.
      This behavior can be changed by modifying or removing the Exclude
      directive in nmap-service-probes, or you can specify --allports to
      scan all ports regardless of any Exclude directive.