I love my burger with mayonnaise. It’s not entirely necessary, but I’ll definitely notice its lack, and if I get served a mayoless burger, I’ll wait to eat until the mayo comes.
This doesn’t apply to fast-food burgers, which I think are pretty nasty already and which therefore don’t really need to be made better; I’ll just eat those with whatever crap they’re served with.
Yes, always, but unless it’s a flavored aioli kinda thing, you only should have a very thin film on the bun, mainly to prevent burger juices from messing up the toast. You do toast the buns, right?
The “secret sauce” that most fast food joints use is just a mixture of mayo, ketchup and sugar. I usually just use ketchup and mustard in judicious amounts, but occasionally will mix a bit of mayo it. Can’t get excited about it either way.
Definitely put mayo on my burgers.
In sit-down restaurants, they often have these honking huge burgers and if you ask for mayonnaise, they give it to you in a little cup on the side. I find that instead of pulling the burger apart, spreading the mayonnaise and then reassembling the whole thing, it’s best just to tear chunks off of the behemo-burger and dip it in the mayo.
I make my own yummy concoction of mayo, mustard and a bit of cayenne to put on my burgers. But that’s the only way I’ll eat mayo on a burger. If I can’t have my own sauce, I just have ketchup and mustard.
No Ketsup, no mustard… if I have ANY dressing on a burger it would be mayo. But it’s not a must. Sometimes I do, sometimes I don’t. 'cause that’s the way I roll.
Mayo, pickles, and sauteed onions is all you need.
If a burger is improved by ketchup it is a bad hamburger.
That’s not true of mayonnaise (in my opinion of course), but the answer depends on the burger, what else is on it, and the bread involved.
Note: It has been 20 years since I last ate a hamburger as I don’t eat beef. So for me we’re talking turkey burger.
I always look forward to silenus’ posts in food preference threads. 
I like it with mayo or without. Like most things, anything fatty tastes good but is probably bad for you
Come the Revolution, comrade… 
I’m ecumenical when it comes to hamburger saucing. I like them with ketchup, mustard, BBQ sauce, even Thousand Island and its mutations. But plain unadulterated mayo is just…wrong. Totally wrong flavor profile for me.
When there is lettuce and tomato on the burger (which is a very good thing), there should properly be mayo to go with them.
There are other sorts of burgers for which the condiment rules are not necessarily the same.
“I’m all in favor of burning down orphanages; that’s good clean fun. But eating by candlelight, that’s a crime against humanity.”
You have the food opinions of a Batman villain.
Mayo is pretty much pure evil.
At home, the only condiments I use are mustard and relish. But I usually like the mayo-based “secret sauce” that restaurants sometimes use.
Thank you! Nicest thing anybody has said to me today. I feel a little tear starting to well up…
Only if there is lettuce and tomato on the burger. Good spicy mustard is mandatory.
Mayo is required on a burger. No ketchup, thanks, unless there’s no mayo. Then I’ll settle for ketchup.
All of your answers are more emphatic than I feel, but I voted Hell Yes. I like mayo on burgers. However, I’ll still call it a burger, as well as eat the thing, if it lacks mayonnaise.