Most Helpful Guy
It depends on the maturity of those involved. I prefer larger age gaps, up or down, because I find it a lot more interesting. But for it to work you have to have similar personalities and interests. I love learning, and if a partner also loves learning (which is a trait I look for in a partner), then the age gap works out to be an advantage.
Take something like movies... if you have similar taste, similar interests, you are going to be able to learn about a lot of movies you may not have been exposed to. A person older will have seen different movies, movies that you would like if your tastes are similar, but haven't seen. Likewise, the younger person will have had different movies marketed to them, and thus seen movies the older partner may have missed. It works similarly for music, books... any kind of entertainment, really.
The coolest part (for me) is that it also works for philosophy and politics. Different generations are exposed to very different propaganda growing up. If you have similar viewpoints, sharing philosophy becomes incredibly interesting, and opens up new ideas and new avenues for intellectual exploration that is simply not present for someone that grew up in an identical situation as you.
Most Helpful Girl
I suppose it would be if the two people have and want the same things out of life in a relationship.
But I don't see that happening between an 18 year old and a 52 year old. It's probably extremely rare.
For just sex? No. They need to be 18 and above (16/17 here for some states, but the general rule is 18 to be safe) and then it's simply a number.