I've been to restaurants that are supposedly decent, and I don't think there's anything off about my cooking - others seem to find it palatable enough, (though whether they'd tell me or not if they didn't is questionable.) I've tried cooking with expensive ingredients and cheap ingredients - and there's a difference in texture but not really much in the taste.
It's not like I can't recognise tastes but the response is just, 'Meh. Oh, yeah it's food flavoured like [whatever]. That stuff you eat so you don't die.'
Take standard supermarket vegetables: nothing special there. Know someone who grows them themselves? Try them. Taste the difference? Suddenly vegetables are worth eating again.
Take a bad dessert: it's got all the right ingredients, but it tastes meh. You've just ingested half your daily calories eating meh. Now try a good dessert: omg how did they do this.
That's the difference.