no ddos protection, lousy routers, single points of failure everywhere (on old servers that are about to die), running their racks very near electrical capacity (too many servers load up at once, breaker trips), way oversubscribing bandwidth, not doing appropriate preventative maintenance, downtime because some tech slips up when editing routing configuration, downtime because some tech trips over your power chords (honestly, a top cause of downtime), downtime because another customer in a shared-colo environment trips over your power chords, etc. the list goes on and on and on.

and, worst of all, you're at their whim -- if they decide, for whatever reason, to unplug you, that's it. we prefer to eliminate anyone who has the ability to take our service down :)