The phrase "unmitigated failure" means a complete and total failure without any efforts to lessen or improve the situation. It implies that the failure was absolute and not reduced or minimized in any way. Full definition
However, in terms of seat share its night was an unmitigated failure — the party's only MP is the Conservative defector, Douglas Carswell. (theguardian.com)
In other words, Franklin's attempts to protect its fees with active ETFs has, at least thus far, been an unmitigated failure. (simplysafedividends.com)
Decades of supply side / legislative approaches «an unmitigated failure?» (blogs.bestfriends.org)