Libertarians get more wrong than right. My assessment of their failings is as follows:
- their faith in unguided economic processes is naive
- their skepticism of organized human behavior is dogmatic
- their understanding of social behavior is almost nil
- their understanding of social hierarchies is nil
- their attention to risk and to second order effects is severely deficient
- their understanding of political behavior is grossly deficient
- their conception of morality is limited and inflexible
- their understanding of entropy, decay, and fragility is severely deficient
- they do not appear to understand non-economic drives
In addition to this, libertarians seem affected by innate mental problems:
- their psychological development is stunted
- they exhibit no loyalty outside immediate personal relationships
- they are glib and argumentative
- their personal tastes are crass and childish
- they are hedonists
- they appear to be completely lacking in genuine altruism
Everything libertarians say is distorted through this prism of shortcomings and defects, so that when a libertarian opens his mouth about regulations, what comes out is usually seriously wrong. Even the basic assumption that the primary obstacle to economic well-being is overregulation or other "inefficient" side effects of governance is based on erroneous thinking. I have never once seen a libertarian address the reality that as human activity scales up it requires more and more effort to put into order (hence regulation)--this absurdly obvious fact goes unmentioned, or if it is mentioned is immediately dismissed.
The libertarian usually assumes that without regulation (or most of it) we'd be living in the best of all possible worlds--he is a stupid modern day Candide. Libertarians love to cherry pick regulations or ignore context--I remember John Stossel pulling a stunt where he setup a lemonade stand in a city and then wouldn't let anyone buy lemonade because regulations forbade it. This was supposed to show the silliness of overregulation, but it only showed the silliness of Stossel.
Libertarians are mostly wrong, and proof of their failure is that despite overrepresentation in the media they are politically ineffective. They are incapable of advertising their ideology in ways that do not ultimately repulse most serious people. (More galling is that despite being anti-conservative, they are used to speak on behalf of conservatives.) They aren't even noble failures, they're just fools.