Why do some people have an aversion to anything that could be considered "diet" food?

I have an aversion to sugar free products that are supposed to have sugar in them or they’d suck, like candy, or fat free products that are nothing but fat or they’d suck, like sour cream. What I’m referring to are regular, naturally low calorie foods that some people would actually avoid because…diet.

For example, I’d been asking my husband to bring home some plain popcorn. I love pop corn. It has virtually no calories and you can chow down for an hour. However, he kept bringing home “extra buttery popcorn,” and kettle corn, which has sugar on it (blech. Kids wouldn’t even eat it!) That defeats the whole purpose of low calorie food.
He kept saying they didn’t have any regular popcorn, so the next time we were at the store together I found some. I showed him and he said, “Yeah I saw that, but it says ‘approved by Weight Watchers’ on it. Why would anyone want to eat that?”
I found that so odd! It’s… pop corn!
When he made some of that nasty kettle corn when the kids were here the other day I commented on how gross it tasted.
He said, “Well, it says ‘Weight Watchers’ on it so I figured you’d like it.”
I said, “I guarantee you it does not say ‘Weight Watchers’ on that kind of pop corn!” And it didn’t.

Another time, years and years ago, when I changed my eating habits to ingest fewer calories I “invented” a really yummy burrito. The beans and the cheese are fattening so my purpose was to use half of the beans and cheese I normally would (OK. I still cheated on the cheese!) and replace them with lettuce, tomato and green onions. Instead of sour cream I just added extra salsa. It is SO good. It’s a staple of mine to this day. (I was making regular burritos for dinner one night and my then-husband kind of complained because mine was so big and fat where as theirs were regular size. “Why can’t I have one that big?”
I said, “You can. I just have to take out beans and add lettuce and tomato.” He made a face and never brought it up again.)
I had a friend then who was very over weight, by at least 100 pounds or more, and constantly fighting it. She made a comment that I had been losing weight recently, and I told her about my burrito (among other changes I’d made,) but made the mistake of calling it a “diet burrito,” as a joke.
She grimaced and said, “That sounds just gross!” and refused to consider it.

What is up with those reactions to naturally low calorie foods when they’re presented in certain context?