Mudders (a racehorse able to perform well on a wet, sloppy, muddy track).
Watch hoses descended from Mr. Prospector or a proficient mud sire such as A.P. Indy.
Sires:
~ Mr. Prospector.
~ A. P. Indy, though widely regarded as one of the top sire in the country was overlooked as a mud sire. He is simply remembered for his greatness, not for his skill in the mud.
Other sires: Avenue of Flags, Boundary, Capote, Carson City, Cee's Tizzy, Danzig, Dehere, Kingmambo, Lord at War, Memo, Not for Love, Nureyev, Quiet American, Unbridled's Song, and Valid Wager.
You can always check the 'Tomlinson Ratings' - Every horse whose sire and maternal grandsire have had a meaningful sample of offspring is assigned two Tomlinson Ratings - one that assesses the horse's likely aptitude for grass and one that does the same thing for muddy or sloppy tracks. These ratings, which have been updated historically twice a year and will now be updated quarterly, are derived from an analysis of tens of thousands of race results on turf courses or wet tracks. The ratings, which appear next to the Turf and Wet headings in each horse's career box, can range from 0 (totally unsuccessful) to 480 (spectacularly successful.
Many mud sires start as overlays, so jump on them when possible.
Maybe another answerer will name other sires as well. :)
Added Note:
Horses sired by A. P. Indy, Carson City, Danzig, Dehere, and Quiet American often have won races on off tracks at Saratoga.