Sorry - It's been asked before!

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I would recommend that you try

mydomain.com/freesites/BareNakedGranny/.html files (site with preff recips or clean page )
mydomain.com/freesites/BareNakedGranny/grany/.html files
mydomain.com/freesites/BareNakedGranny/milf/.html files
mydomain.com/freesites/BareNakedGranny/mature/.html files
mydomain.com/freesites/BareNakedGranny/[granny-keyword]/.html files
as well this way you will know that your sites are more organised..
But I agree
mydomain.com/freesites/BareNakedGranny/.html files
mydomain.com/freesites/Bare-Naked-Granny/.html files
mydomain.com/freesites/Bare-NakedGranny/.html files
mydomain.com/freesites/BareNaked-Granny/.html files
mydomain.com/freesites/Bare_Naked_Granny/.html files
mydomain.com/freesites/Bare_NakedGranny/.html files
mydomain.com/freesites/BareNaked_Granny/.html files
mydomain.com/freesites/Bare-Naked_Granny/.html files
mydomain.com/freesites/Bare_Naked-Granny/.html files
is a good structure. but you should probably try this

mydomain.com/freesites/BareNakedGranny/.html files
mydomain.com/fresites/Bare-Naked-Granny/.html files
mydomain.com/feesites/Bare-NakedGranny/.html files
mydomain.com/fs/BareNaked-Granny/.html files
mydomain.com/free-sites/Bare_Naked_Granny/.html files

but its much more complicated

I think
mydomain.com/freesites/BareNakedGranny/.html files
and
mydomain.com/freesites/Bare_Naked_Granny/.html files

is the same for google and it will see mirror much faster.. (use '-' instead)