But that isn't entirely what I meant- the Founders aren't going to hold the Jem'Hadar at fault for not conquering the AQ- they did what they were told, with their allies.
You never know, the Founders might decide the Jem'Hadar have passed their used by date and create a new race of soldiers. So there is also the general case of "Victory is life", if the Jem'Hadar can't bring the Founders' victory then their worth to the Founder is nil.
I'm thinking on a smaller scale- if they were given impossible odds, what would be the result of losing? But a Vorta would do it to be a jerk, a Founder would know the Vorta was being idiotic, a Jem'Hadar is always 2 steps ahead of the Vorta so...
If they were given an impossible situation the result would most likely be death. Actually the most likely thing the Founder would do is nothing, the Jem'Hadar are expendable and easily replaceable and wouldn't bat an eyelid (if they had them) at the Vorta executing Jem'Hadar for failure. I don't think we ever saw it happen on screen, but I wouldn't be surprised if the Vorta did chain of command adjustments via executing Jem'Hadar for failing the Founders.
The only time I can actually remember the Founders' executing people for failing and using the fear of death as a motiver is when the Female Founder ordered the Vorta failing to find a cure for her disease to be killed and replaced with new clones.