After upgrading my Cygwin installation (which fixes some annoying socket problems for me) one residual problem was the display of certain characters in man pages. As this problem seemed to effect the emboldening of options like '-d', this made man pages virtually unusable. So, I then found, relatively empirically, that this can be fixed by adding the following lines to your ~/.profile file:
LANG=ISO-8859-1 export LANG
If you make this update, and open a new window, you should find that man pages return to their former, readable, glory.