If you're one of those people who loves salsa but can't stand pico de gallo, and who relishes marinara sauce but turns their nose up at a freshly diced tomato, you're not alone. There are plenty of people who hate raw tomatoes but love them when they're fully cooked. The good news for these haters is that their visceral distaste for tomatoes probably isn't just psychological. There are a few hypotheses as to why some people hate raw tomatoes but love cooked ones.
The first thing to understand is that tomatoes are complicated fruits with a complicated flavor profile. There are about 400 different volatile compounds in a tomato, each of which has an impact on its taste. As plant molecular biologist Harry Klee of the University of Florida told Wired in 2012, no one is entirely sure which of these compounds creates the, for lack of a better phrase, essence of a tomato. By contrast, as Klee said, "With something like a banana, you can identify one volatile compound that you smell and say, ‘Aha! It’s a banana!’ With a tomato, it’s not that simple."
So there's one hypothesis that some people scoff at the scent of tomatoes because they're genetically predisposed to be more sensitive to certain compounds than others in the tomato scent medley (though there's still more research to be done in order to fully understand which compounds elicit which responses from humans, as well as the genetic component involved).
Other people can't stand raw tomatoes because they taste blood when they bite into it, and there's a scientific reason for that, too. As Harold McGee writes in his book On Food and Cooking: The Science and Lore of the Kitchen, "ripe tomatoes have an unusually large amount of savory glutamic acid (as much as 0.3% of their weight), as well as aromatic sulfur compounds." These two compounds—glutamic acid and sulfur—are more common in meat than in fruits or vegetables, and so when some people smell them, they associate them with meat. This combo of compounds, according to McGee, is also why tomatoes smell so bad when they rot.
The other reason that some people hate raw tomatoes is because many commercially available tomatoes are just really bland and don't taste good. That's because over time, tomatoes in the United States have been bred for sturdiness, to handle being shipped across the country without getting bruised, rather than taste. So most of the tomatoes that Americans eat are beautiful to look at but often need seasoning to become really delicious.
The good news for people looking to get their hands on tastier tomatoes is that Klee and his team recently conducted a study of flavor compounds in "398 modern, heirloom, and wild accessions" of tomatoes and, in a paper published in Science, they figured out which bouquet of naturally occurring chemicals and flavor compounds are most associated with delicious tomatoes. The hope is that this kind of research can bring flavor back to grocery store tomatoes without sacrificing the sturdiness—and maybe even finally turn the tomato haters into lovers.