Is it still safe to eat/use? Or should I toss it? Note that house temperature averaged in the mid-60s (F) during the time it was on the counter, and it was closed tightly. (And please, no Miracle Whip versus “real” mayonnaise arguments, 'k? Pretty please?)
According to Alton Brown, mayo is acidic enough that bacteria will not grow in it. To my mind Miracle Whip is close enough that I wouldn’t worry about it. YMMV of course.
I do this all of the time with the mayonaise. Do I ever get sick? No. Do I tell my guests? No.
You can eat Miracle Whip?
Mayonnaise salads are one of the leading causes of food poisoning. Yes, the mayo is acidic and if commercially-prepared, probably safe on the counter overnight, but once you’ve opened the jar and stuck utensils in it (which may or may not have been perfectly clean), you can still grow nasties in a jar of mayo. I wouldn’t be leaving mine out on the counter regularly. Forgotten out one night? I don’t know - my first reaction says it would be okay, but the golden rule of not poisoning yourself is “If in doubt, throw it out.”
And for the record, I’ll eat yummy, tangy Miracle Whip any day of the week before I’ll eat the devil spooge that is mayo. 
Well, I found this information at the New York Times
Looks to me as if I ought to be safe to use it again.
Thanks, all.
Just think about the way fast-food restaurants dispense room-temp packets of mayo…or the fact that it contains so much acid…or that you can make a bologna and cheese sammy in the AM and eat it in the PM safely even if you haven’t refrigerated the bag lunch.
As long as you’re not leaving the opened jar out of the fridge on a regular basis you should be fine.
Or you could just buy another jar…it’s still pretty cheap!
My Ex MIL would NOT keep her Miracle Whip in the damned fridge. I don’t know why. Even when I asked, she said she liked it not cold, and it didn’t hurt anything.
It tasted old, and I switched to mustard at their house.
Anyway. None of us died during those few years.
As a matter of fact, they ALL still survive.
I now keep mine in the fridge.
It’s very likely safe. But then again- how expensive is a new jar of mayo?
There are both acid-loving and salt-tolerant bacteria. Like I said earlier, once you’ve opened the jar and stuck un-sterile things in it, all bets are off. Those packets left on the tables are single-servings and are sterile until opened.
LadyMack, another rule of thumb for not poisoning yourself is not eating food that tastes or smells anything but fresh and normal - I think you made the right call by not eating it, even if no one else seemed to get sick. Jeeze, I don’t know why people play around with this kind of stuff - the fridge is right there, in damn near everyone’s home. Maybe people need to read some case studies of how easy it is to poison yourself with food to take it more seriously.
Since Miracle Whip is 98% plastic & 2% preservatives, I can’t see how it could be dangerous.
Now actual mayonnaise would be another matter. If I left it out overnight I’d pitch it, and I’m pretty far towards the “eat stuff off the floor & who much cares about spoilage” end of the spectrum.
Ugh, as a kid we were forced to eat Miracle Whip instead of mayo on our sandwiches that we took in bag lunches because of the lack of refrigeration. Mom said mayo would spoil, but MW would not. I always chose mustard instead. I hate MW to this day, and now I find that my suffering was totally unnecessary. Sigh
Why are so many people so freakin’ emotional about MW vs Mayo? I switch back and forth. I get a little tired of one and get the other. Occasionally I’ll get that “sandwich spread”, with the relish mixed in, but I get tired of that before it’s gone. 
Also, some people seem proud of not using either. Proud enough to brag, and say “no mayo” loud enough for all to hear.
mangeorge smells affectatious behavior here.
Peace,
mangeorge
In my case, it’s because I really like mayo and really hate MW. MW tastes too sweet. If I wanted a sweet sandwich, I’d make PB&J.
I also don’t like how many people equate the two, like they are essentially the same. When my husband and I were dating, he took me home to meet his mother. Somewhere in the course of the visit, we went on a picnic, and his mother asked me if I wanted mustard or mayo on my sandwich. I of course said “mayo” and thought in my head, “Thank goodness none of that MW crap.” Of course, I bit into my sandwich to the horror that was not only MW, but fat-free MW which has some sort of pinkish tinge that the regular stuff doesn’t have. Disgusting! It was all I could do to choke it down with a smile of my face. And now she thinks I prefer “mayo”. I do–real mayo, not pink MW.
At least my mom never called MW “mayo”. She has her reasons for preferring MW, but she knew they were different. Had his mom said “MW”, I’d have picked mustard. I guess I’m passionate about it because MW masquerades as something good.
Source: Mayonnaise - Wikipedia
Source: http://www.minimus.biz/detail.aspx?ID=7321
Source: What's the Difference: Miracle Whip vs. Mayonnaise. - Neatorama
YMMV.
Good OP. But, since this is the Dope, trying to prevent posters from offering their opinions in General Questions is like spitting into the wind. :mad:
Moving this to Cafe Society, where they still give factual answers, and opinions are welcome.
samclem GQ moderator
I think it’s because there’s a group of people in the world that don’t differentiate between MW and Mayo, and us mayo-lovers have been burned more than once by being offered mayo, saying “Yes!” then taking a bite and realizing it’s MW. To me, MW tastes so sweet that it’s like covering your sandwich with some sort of weird sugar-vinegar sauce. Yuk.
Heck, my own mother thinks MW = Mayo. I grew up thinking it was the same thing. Then I discovered the true wonder that is mayo, and suddenly I realized why people actually like it. Mayo tastes good. MW tastes yucky. If you like it, fine, but please don’t assume that I do, and don’t give me MW when I ask for mayo!
Amen! Only a 'tard space alien without tastebuds would not realize that there is a significant difference between the two. I actually can sympathize with those poor souls cursed to be brought up in a MW house. It is still the devil’s semen to me.
I’ve left mayo out overnight way more times than I care to admit. I’ve almost never gotten food poisoning (I should not have eaten that duck left out in hot weather), let alone died. But, since I eat all kinds of foods that would freak out the sanitarians, I have a superior immune system that has up to this point managed to protect me.
I often don’t bother putting my mayo away. Everyone I know frets about this, but it has never made me sick.
If you don’t exaggerate, nobody’s going to listen to you.
Like I said above, I use both interchangeably and can definitely taste a difference. But I enjoy that difference and use it to my advantage (variety, mostly).
Miracle Whip is sweeter, but not nearly as sweet as a certain poster claims. Methinks said poster is simply trying to make a point. In fact, it has a certain tartness (under the sweetness) that’s missing in Helman’s.
I like to make my own mayo, and it is very easy, but I’m usually too lazy.
Oh, for potato salad, the regular kind, it’s MW plus some Grey Poupon, hands down.