It was Sale's first win on Bath soil since April 1998 as second-half tries from centre Elvis Seveali'i and flanker Magnus Lund saw them home.
Fly-half Charlie Hodgson ensured there would be no Bath fightback as he kicked three penalties and a conversion to take Sale back into first place above Wasps.
Bath had to content themselves with three Olly Barkley penalties. But despite the fact they boast unbeaten records in this season's European Cup and Powergen Cup competitions, their Premiership form remains disappointing - and they are more than 12 points adrift of a top-four play-off place.
"It is really disappointing in the context of how we played in December when we had four wins out of four and scored 13 tries," said Foley, who will now work alongside newly-appointed head coach Brian Ashton.
"We definitely wanted to play [on Monday], but our execution was very poor. When you play the best team in England the basics have to be good.
"Sale have got a lot of dangers - and they have the greatest depth in their squad in terms of international players. I also thought Charlie Hodgson was fantastic - he is undoubtedly the best number 10 over here."
In Monday's other Guinness Premiership game, Leicester saw off Saracens 34-27 at Welford Road.
Head coach Pat Howard hailed his Leicester heroes after seeing them get their season back on track.
The Tigers responded to their defeat at Bristol six days earlier by running in three tries en route to victory, surviving a torrid spell in the second half when they were reduced to 13 men after Ben Kay and Graham Rowntree were yellow-carded.
Howard said: "Our guys worked very hard and that was a great piece of play.
"They were making tackles and driving Saracens backwards.
"Saracens are a good team and the game lost a lot of momentum with the sin-binning. That made it go down to the wire."
Howard made 10 changes to the side beaten at Bristol and that included leaving England winger Tom Varndell on the bench.
Varndell responded with a sparkling try after 75 minutes that put the game beyond the visitors.
Howard said: "The team is picked on form. Tom came out with a point to prove and he proved it."