Professor Snape, Anne. 
In the Dresden universe, magic not only effects electronics badly but even on purely mechanical devices has a sort of magnified Murphy’s Law effect. In other words, if your semiautomatic will ordinarily jam or misfeed on average once every thousand rounds, in the presence of magic will do so every four or five rounds. The point of a revolver is that there is less that can go wrong because something was a thousandth of an inch off.
Why does Argus Filch keep his job? You’d think Hogwarts would want someone who can do magic as their janitor. Or why wasn’t he fired for collaborating with Umbridge?
And after what happened to Mrs Norris, why on earth does he want to keep that job? If something happened to one of my cats that could easily have killed them, and whatever it was happened because of my job, I’d put in my notice there and then, and look for something safer. It’s not as if he likes his job, either. He’s got a sucky job in a dangerous environment.
I’m sure there are problems with looking for employment with an apparent gap in your resume, but is that really a problem for janitorial-type jobs? He could even go freelance as a Muggle housecleaner if he wanted to. At least Mrs Norris would be safe, and he wouldn’t have to deal with poltergeists or teenagers who look down on him because he can’t do magic. Being a janitor at, say, the Ministry of Magic or Gringotts would be another job that would suit him better than Hogwarts. Lots fewer kids at either place. If you hate kids, working in a boarding school probably isn’t the best career choice, y’know?
Filch could definitely use some career counseling.
He is the worst of both worlds. He has no magic and yet lacks education and knowledge about the Muggle World to sirvive there. He was probably delighted to get whatever job he could.
What those folks need is a paladin to check all prospective teachers with detect evil. Of course, it would make for some mighty short books, but it would at least quell all the angst about Professor Snape.
Harry: Professor Snape is evil, I tell you! Evil!
Celeste the Paladin: (invokes detect evil) Nope.
Harry: But how do you know he’s not using undetectable alignment?
Humbert the Warden Archon: (invokes unerring assay, which is unaffected by most methods of alignment concealment) I’m sure. He’s a solid N.
Snape: You see? I’m not evil, I’m true neutral! Oh, and I am totally not a woman.
Harry: You would fireball a peasant, though.
Snape: Really, Potter. A 3rd-level spell on a 0-level peasant? And you wonder why I doubt your academic skills.
Flynn the Fine: (sings) Shut up, dear Harry, rest your head, or I’ll let the Death Eaters kill your ass dead! (dies)
I was just going to say that. He mentions in the books that generally stuff made after 1950 tends to malfunction and or fry when he’s around.
Of course, there’s another reason Harry has a .44 magnum, the most powerful handgun in the world.
I think in this thread we should specify which wizard Harry we’re talking about.
Well, yes, but I think the handgun would have solved Mr. Potter’s problems quite nicely as well…
The Second task, scuba gear.
^
LOL. Made my day.
It depends. If you hate kids, and therefore want nothing to do with them, then working in a boarding school isn’t your best choice. If you hate kids, and therefore delight in tormenting them, then caretaker of a boarding school with fairly loose rules about what you can do to the students is ideal.
Insurance would be another good thing. Especially in Hogwarts, lots of kids with wands hexing each other. Wonder what the premiums would be like.