Why don't you go out and put 50,000 miles on your HD and let us know! Mine however, still runs strong and doesn't leak a drop of oil. '03 Heritage with 58K miles.
The older motors (shovels and earlier)used to like to leak oil and were a bit more tempermental. The current motors are very good. Would I like to have an old shovelhead to play around with? Yes. But I'd feel much better riding cross country on my twin cam.
I put 64000 on my 97fxstc and it never leaked a drop,also cleaned the air filter and put plugs in every spring.Ran great!!...Tell "they",it's all about the upkeep.