The most of old people (~ older than 60), especially women, cause me disgust. Obviously, I don't tell and don't do anything bad to them because of this; I just have no desire to communicate with them or to help them in anything, so I avoid them when I can. It wasn't always that way; when I was young, I believed that we should be kind to them, but the more I grew up, the more I got them know, the less this believe became.
Why? Because the most of them are extremely stupid, extremely conservative and extremely ugly. Extremely. Not saying about being callous toward problems of younger people, total lack of critical thinking, lack of personal hygiene and total lack of taste, which make an important contribution into their ugliness. And, despite all of this, they think that we all owed them.
Of course, there always were, are and will be rare exceptions. For example, I feel deep respect to people like this one: https://en.wikipedia.org/wiki/Ernestine_Shepherd, this one: https://en.wikipedia.org/wiki/Michael_Atiyah and toward several old professors in my University as well. Obviously, I would never miss the chance to talk with people like these or help them when it's necessary. A couple of people at this forum (and at least one person IRL) also told me about their old relatives, who feel interest to new things, groom themselves, behave decently, participate in sports and intellectual activity; I also saw old people, who were friendly toward younger and sincerely had fun with them on concerts, etc (but, unfortunately, only a couple of times in my life). These categories don't cause me negative emotions as well...
...but, unfortunately, as I said, all these people are exceptions. The most people of old age are not like them and match my description above instead. And, in the same time, everyone pretend, that it's not true. Everyone pretend that old people are not extremely stupid, ugly and just unpleasant as persons.
Everyone support this hypocrisy, because everyone know that they will become old, too (if they will not die before this). And after this, everyone want their younger relatives to pretend, that they respect and love them as well.
Society is built on hypocrisy, which continues from generation to generation, and everyone are fine with it, no matter how absurd is it. 
I don't have any solution to this problem. Just wanted to blow off steam.
P.S. You ask, what will I do, if I'll become extremely stupid and disgusting, when I'll become old?
Well, if I'll turn into something, which cause me such an emotions, it will not be me anymore. I don't care about "future me" of this type. If this "future me" will die in loneliness and suffering, I don't care, because it'll be deserved. But I don't think it'll happen, because: 1) I can put my efforts to become different, to become like those old people, which I respect; 2) If, despite of this, I'll feel that I'm becoming a person, which I despise, there is always a thing like suicide. 