I've been both sides of the table many times.
For recruiting staff to work for my team, I think the worst was the person who stank the room out in 10 minutes with stale BO & had wax actually sticking out from his ears (office job). I couldn't cope with CVs or covering letters that used text spellings, likewise ones that had clearly used a spell checker but didn't check the context so the words may have been spelled right, but were the wrong words. And bearing in mind that this job involved authoring processes, exceptionally bad punctuation (not just talking about semi colons here, but random or missing commas & full stops).
Jobcentre was ridiculous, with rules clearly designed to force reluctant people into applying for jobs and no consideration for those really trying. The rule was x applications per day to be done while at the job club thing in the afternoons - which had crappy ancient PCs with ancient versions of software (Internet Explorer v6 anyone???). They were restricted in what sites you could visit, and didn't have access to half the job boards that dealt with my specialism. Also blocked access to many big national recruitment companies. At home I had a high range fully up to date PC.
I was once sanctioned for 6 months for not applying for a job that was 90 minutes commute away by public transport PLUS the walk at either end, paying NMW, with requirements I had no experience of. It took me 30 minutes once to persuade a job coach that the role "planner" means VERY different things in different industries, so as a project management planner I wasn't qualified to do electrical circuits planning. I had a row once when my job coach wanted me to apply for one job that was on one of their "permitted" job boards; that role was one (of many) that you could only access if you PAID the job board a fee to access their "premium" area - totally against Jobcentre rules.
I have 3 versions of my CV, which I tweak for different job applications. I do a covering letter for all jobs that ask for it. I have spent literally hours sometimes on on-line application forms that want every single role I've worked in since year dot - and as I'm late 50's and have done spells of contract work and temping, is virtually impossible.
I can no longer cope with the stress of my former more high powered jobs, and want a semi-interesting admin role. I have been turned down too many times to count for the assumption that as I'm over qualified I "will get bored & leave soon" - despite stating in interview that this is exactly what I want! I know in a lot of cases age discrimination plays a part, as apparently as soon as someone hits 40-45 they are just marking time until retirement - which is exactly the opposite view to the over qualified thing above.