
Working in your pyjamas - not simply because you can, but because you've been too busy doing disaster control to change. It's now 3pm, and you're also starving.
Having to update your CV every damn year, sometimes several times, for different clients and different speciality angles (also different formats). You're always surprised when it comes to stating the length of your experience (Have I done this that long? But I still don't know zilch!), but you still cringe over having to make yourself look good.
Outsourcers who fail to grasp the concept of "free" in "freelancer" - they "assign" jobs to you, without failing to ask whether you perhaps might have a job for another client (gods forbid) in the works. Or, only reply to your enthusiastic "Yes I can take this job, give it to me!" email 3 days later, when you've already filled your week with other (much more boring) jobs and have to (yet again) explain the principle of first-come-first-served using very short words.
Slowly but surely getting a stress ulcer from not giving incompetent twats a piece of your mind - yes, because they're people too, and often you get the impression they're also over-worked and over-stressed, but more importantly because you still need them to keep sending job offers your way.
Having to explain, time and again, that yes, my language has a multitude of grammatical cases, and yes, the nouns and adjectives inflect accordingly, and YES, that's why your oh-so-clever QA tool keeps giving me 3k+ false positives from a job with a barely 5k wordcount (not even kidding here, I'm afraid).
Not being able to blame the middle management for work overload - you ARE the middle management (you're also the tech support, accounting and caretaker).