It depends on the video, for my more viewed videos, I ignore them ALL, I only delete the links, like Amazon associate links, they do not belong in my videos, unless I put them there.
Some of those crazy comments have really helps those videos grow views FAST as people are reacting to other people comments, it's a shouting match.
BUT for my less viewed video, I will delete, block or report the really bad comments.
But remember each comment does count into YouTube's search formulas
There are some days, I am just not up to reading comments also, arghh...
Steve