As a class of people, there is only one factor that ties all of them together under a single ideological umbrella. By all other measures, their opinions can vary wildly.
The capital-L Libertarians, otherwise known as the members of the Libertarian Party, are just the tip of the small-l libertarian iceberg. For those who have chosen to abandon political participation and evangelism, you may never even realize they are libertarian at all.
There are some godawful douchebag libertarians. There are criminal fraud libertarians. And there are also libertarians that are outwardly indistinguishable from everybody else, aside from little things like laughing at something when a joke was not intended.
Do you remember Dennis, the 37-year-old not-an-old-woman from Monty Python and the Search for the Holy Grail? Do you recall how he was attempting to explain the anarcho-syndicalist commune to King Arthur? Anarcho-syndicalists are a type of libertarian. Just as Arthur dismissed him as completely useless, modern mainstream politics ignores and marginalizes most libertarian groups. And they do it to each other, as well. No one is better at denouncing a particular type of libertarianism than another type of libertarian.
I would guess that most of those people are not terribly well educated in the basis of Libertarian thought. That's a pretty naive interpretation of it anyway.
Anyway, I'd love to continue this conversation, but it's probably veering close to (or into) "off topic" territory, so I'll just drop this here.