I have had, and still have bad experiences not just in writing.
It's just my luck, or life at this point, and because of it, I feel I'm incredible pessimistic, and cynical.
When I first started. Many harsh comments about grammar, and topics, and themes. They unraveled pretty much everything about my characters, and plots. It was beyond annoying, but I don't as much mind, "I think this character, scene, or action was dumb because ____". okay.. understood. But most were just "this part sucked." "I didn't like x character." and I would ask why? and never get a response, but they'd keep coming back nit picking about something else..
Been harassed by online mob mentality.
Had normal sfw, rule abiding stories flagged for seemingly no reason.
had accounts (multiple) banned.
accused of stealing when I didn't (just opening to the first pages of both stories would have proved to anybody with eyes that I didn't)
have had friends attacked online for no reason other than being associated with me
have had stories stolen and I was the one who got in trouble for PROVING I was right... wtf with that one
but to answer your thread question:
WORST experience as a writer?
Trusting an Ex to read, or learn anything about my writing hobbies. You think, okay, this person is really special in my life, and wants to know more about me. We've been dating a few months, and we've always gotten along.
SHE cheated, NOT JUST ONCE mind you. HER friend tried to make a move on me saying I deserved better, TRUE, BUT we were still arguing, and hadn't officially broken up, so, I refused, nothing ever happened not even a kiss (I get it, stupid me, I guess), anyway SHE broke it off saying I cheated?? So in her little twisted mind game. She remembered, and took note of online name, and started spamming my stories with negative reviews, bad comments, even attacking other commenters. I didn't know who this person was until they called me 'a cheater'. Which no. and second. it was her. but BECAUSE of her. other people also started accusing me of things. even other writers. which lead down the rabbit hole of most everything listed above. Wattpad sucks.
At this point I don't even care anymore about what happened, the only thing I do wish though: I wish I had saved my stories offline, instead of writing them directly on Wattpad. There were a few good stories I wish I could have shared here. I was dumb, and new to writing at that time. I don't normally call any of my ex's names, but she in particular, was a b***h, and a psycho. F*** you Chrissy.
Don't trust anyone with your personal hobbies... Those are for you.
AND save EVERYTHING offline, and keep backups. Losing work sucks.