@PatNY - personally I 100% agree that the default should be to not search the comments fields. It is one of the first things I change when I install calibre for other people. However it is a battle I briefly tried to fight and lost a long time ago. The concession I did help win was in getting a preferences option available (thanks to chaley for the work) so at least users could do it without modifying source code.
I'm guessing the other devs haven't changed their mind on this issue by now, but you never know
And yes, not sure what special juice itimpi was drinking today when he posted, but searches are most definitely an
and not an
or when not specified.