'utterly incompetent' is a correct and usable phrase in written English.
You can use it when you want to describe someone or something that is exceptionally bad, inefficient, or inept. For example, "He proved himself to be utterly incompetent as an accountant."
Only one young man was utterly incompetent, and my heart warmed to him.
But when they are utterly incompetent and their enterprises collapse, the taxpayers pick up the tab?
The day after that, he survived an utterly incompetent revolt against his re-election as speaker of the House.
Tantawi and his colleagues proved utterly incompetent in running the nation and were replaced, via a revolutionary election, by the Muslim Brotherhood's party, led by President Mohamed Morsi.
We dare say (and hope) that the political party which puts forward an utterly incompetent candidate will lose even in its registration stronghold".
They are not fit for purpose, utterly incompetent and have overseen the transformation of the Britain's electoral process into a circus worthy of a corrupt banana republic".
A powerful series by William Glaberson of The Times has painted a devastating portrait of a lackadaisical court culture in which the main actors in the Bronx seem utterly paralyzed or incompetent.
Andrea Leadsom, the MP for South Northamptonshire, said to McLoughlin: "I urge [you] not to take the word of [your] departmental officials but to look at the impact of the exceptional hardship scheme on many constituents whose lives have been utterly destroyed by incompetent and completely inconsistent panels.
He surrounds himself with aides who are either wildly incompetent or utterly defeated in their attempts to domesticate the mulish and bizarre object of their attention.
We are in a national emergency as an alarmingly incompetent and utterly amoral gang prepares to destroy the climate, human rights, the foreign policy positions the US has relied on for stability since the second world war, and more.
Reckless incompetents commit utterly predictable suicide, endangering rescuers".
