Do you every complain about food in a restaurant?

I might say it's not great, if asked. I wouldn't send it back, I'd leave it, as I wouldn't trust it to return unmolested, people can irrationally take things very personally. I don't want the kitchen to spit in my dinner.

No because I'm scared they will spit in or do something to my food

Definitely - we had an awful meal the other week - cold food, half the options unavailable, veges didn't come out until after we were all nearly finished. We spoke with the manager and they refunded all the food!

Only if it’s undercooked and dangerous to eat.

No because as a student I worked in restaurants and still remember the attitude from the chefs when people needed their meal tweaked.

I have done several times. I didn't recently in a small pub - it was a bit of a Slaughtered Lamb kind of place and I was sure the chef would have us thrown out if we criticised his cooking. It wasn't inedible anyway, just badly cooked and bland.

Also I’m vegetarian so what I order tends to be safe/predictable as many restaurants don’t have a great vegetarian menu! Nothing much to complain about with salad and fries

Of course.
Ive only needed to a couple of times, but been respectful and polite and got the result I wanted.

To be honest it sometimes depends on who I’m out with. One of my friends complains regularly for example, I daren’t complain as I feel bad for the staff when she does. I tend not to make a fuss.

Most of the people I go to dinner with are easy going so we don’t really complain. However I did go out with a large group for my friend’s birthday and everyone unanimously agreed to take the service charge off - I think if I was by myself, I’d just pay the service charge.

Looking back, the only time I have complained about what I was served has been about the drinks rather than the food. Some extremely bitter cocktail for example.

Only to have a problem solved, not to get money off or make a point. That said, many years ago I responded honestly to being asked how my meal was. It had had a really unpleasant lime sauce that overpowered everything and I said so. Despite eating every last bite and with no intention of saying anything if I hadn’t been asked, the restaurant insisted my whole meal was free. Was teased by friends for ages about that!

If the food is horrible, under/overcooked or raw then yes I will say something. If it's really good I also leave a tip.

Yes
Only fair to give them chance to rectify a problem
Better than giving them a bad review ..which i feel is unfair if you don't tell them about an issue

I did once, because my burger was pink inside. Your burger shouldn't be pink inside.

Last time I complained was at a Toby carvery - food was cold, a potential food safety issue. They offered a 50% discount and free dessert and after 45 minutes waiting we gave up waiting for the dessert. We won't go back to that branch.

Yes if it was really awful I would. Last time I mentioned something to waiting staff was some crab cakes we'd had that had pieces of shell in them. I just flagged that it was good to know they were homemade, but just to feedback to the kitchen so they could check future batches more thoroughly. We'd eaten them entirely (well aside from the shell fragments) as they were delicious.

They came back and offered us a dessert for free which was unexpected but appreciated.

I would only complain if it was really dreadful (eg. undercooked chicken or food totally cold) or if they got my order completely wrong

If it's just 'not great' (eg. bland, too dry, too salty or whatever) then like you I would just make a mental note not to return, or if its somewhere where I normally enjoy the food I would just avoid that dish if I return

When I'm out with friends who make a big fuss if they're not happy with their food it really makes me cringe and spoils my enjoyment of the evening

Yes of course. And I’m sure most restaurants would prefer you to tell them that there’s something wrong and have them attempt to rectify it, than say nothing and never return.

I do if it's bad, but I make a judgement call based on price, quality etc so it tends to be either an expensive meal which was so so, or really bad if cheap

Of course, why wouldn't you?
I do it in a calm and respectful way and explain what the issue is and I always get a discount or the item taken off the bill.
I only do it if there is actually something wrong such as too cold, burnt etc arther than me just not liking it though.
My family say I am really good at it, I manage to never piss off the staff and we get free stuff

Sometimes, yeah - either to get the food changed (e.g. if it's cold) or to alert staff to a problem (e.g. something tastes off or over-seasoned). I wouldn't do it to get money off or free food. I also wouldn't write a bad review unless the service was very rude.

If the food is inedible/I won't eat it, then I'll complain eg too salty to eat, burnt or there's a hair or even an insect in it. I once had a worm-type creature wriggle across my hot meal and definitely complained about that.

I generally just want the food replaced with something I can eat and am always polite and, except for the worm incident when I screamed, do so quietly

I do if it's the wrong order or undercooked/cold etc but not if I just don't think it's cooked very well

If it’s really bad I complain , I’ve often sent stuff back if it’s cold etc

I usually do politely tell them if there's a problem with the food. Most restaurant owners would want to know, because they want happy customers. The key is doing it politely.
Actually once I complained & the boss said how pleased she was that I told her. We've gone on to become friends!

Yes. If there is something wrong with it. it goes back.

I can think of two occasions, one at a theatre bar when my burger arrived in a bun with a large patch of green mould on top. That went straight back.

And once in a Michelin starred restaurant when my creme brulee arrived so badly burned & black that the waiter saw my face, saw me draw breath to reject it, said 'no, perhaps not' and did a u-turn back to the kitchen. 😀

But it doesn't happen very often. I seldom go out to dinner but when we do go, we try to choose somewhere trustworthy.