It seems that man -K does not search the formatted output, but the markup source. For example man -K warrantiesgives many manpages which do not contain the string warranties, like xcalc(1). Also, searching for strings containing special characters is very difficult: man -K 7 '\f'gives a lot of pages not containing \f. man -K 7 '\\f'does not seem to display false positives, but it also does not display ascii(7), which contains the string \f.How do I get around this?
Dealing with manpage search
man