Sales margins are not what they fear, that has become a subjective term. Having the right talent to produce and keep them producing or just keep them at all is what they've had the hardest time with.
I would say if you are looking to find a good sales manager, you'll be looking for the recruiter that knows how to not just motivate but inspire and support good talent.
If they have a high turnover in their history when managing a team, it may be because they can't keep good talent, then again if it starts rough and levels out, they may be your keeper.
Do what you must to ensure you got the "right person" for the job with that in mind.
Checking references now is becoming a bigger must than before simply because you want the right talent too.