Dots cannot miss "tics" once cast on a target.

Bio and Bio II cannot miss because they do not do any initial damage on a target, neither can contagion.

I have no idea how much my pet actually misses, as there is too much going on to really tell, but for the most part despite the "excessively low" accuracy I have I hardly ever see garuda miss hitting a conflag I'm in or a dreadknight while I'm stunned and have the time to notice.