Sour coffee frequently means the grind is too coarse for the bean or the coffee is not brewed long enough. Both of those are more common problems when working with lighter roasts.
You might experiment with the same bean and different grind settings to see if that helps with the taste you don’t like. Though age of the beans messes with this too which is maddening. Generally speaking though lighter roasts are more fiddly to brew so get messed up more frequently.
This doesn’t ring true to me. My understanding (and experience) is that coffee beans have abundant flavor components which get burnt away by the roasting process. Brewing issues like grind and proportion of beans/water are a separate class of problems. Is it not possible in your mind that someone just doesn’t like the sharp flavors which are left uncharred in light roasts?
It’s certainly possible people just don’t like light roasts, but _sour_ is a specific flavor profile which frequently has a specific cause, and that cause is more likely with lighter roasts. Which is why I mentioned it.
It’s more simple than that. Acids are sour. Coffee has acids that are transformed by the roasting process. Light roasts do this less. Some people like that taste and others don’t. Those that do like it often act superior and treat the other group as uncultured.
What you say is true, but it is also possible that someone describing the flavor as "sour" isn't experienced enough to have built up the official vocabulary. You see this a lot in tasting cultures of various products, what one person means by X isn't necessarily the same as another person.
> someone just doesn’t like the sharp flavors which are left uncharred in light roasts?
that is always a possibility.
It why you want to have a pro brew up the best cup that is possible from those light roast beans, and test out the flavour.
If you're a self taught brewer, you might find that you've made mistakes, and also mistakenly took those mistakes as the flavour of the bean, thus incorrectly dislike it.
You might experiment with the same bean and different grind settings to see if that helps with the taste you don’t like. Though age of the beans messes with this too which is maddening. Generally speaking though lighter roasts are more fiddly to brew so get messed up more frequently.