I don't mind Heineken, it's alright. Tried a Guinness 1.5 months ago and felt the same way about it that you feel about Heiny. It's all a matter of preference, but part of the reason that Heiny is so well liked might be from people just having a different beer after years of drinking really poor beer(just a theory).
Personally I used to like a local Beer(Kokanee) and thought it was great, but after trying some other beers and not having Kokanee for a few years, one time I decided to get a Kokanee, it tasted like ass. I was shocked how little I liked it anymore and wondered why I liked it in the first place.