I don't think Basho was giving his own opinion about the crow when calling it detestable, he was simply giving the common description for the bird. Most people seem to dislike them, then and now. Basho himself was too in love with nature to hate anything of it.

This is indeed one of those more challenging ones to translate. Not because we can't tell what he meant, but because it is unstated. Do we leave it unstated in English or be a little more explicit? "Beautiful" is inexact. It is more of an appreciation for the bird. A zen-esque feeling of the bird belongs here in this scene and it wouldn't be complete without him, for we cannot have beauty without ugliness, no yang without yin. In this case I'm not sure an English reader could make the connection, unless they have studied Eastern philosophy (which most haven't).

Maybe I should have included this in my post ;) I was kind of in a hurry when I wrote it because I am fighting the flu and wanted to go to bed, hence the shorter description than usual.