(For those familiar with the BHL blog, where they are known to sneak in justifications for using force): The very phrase 'Bleeding Heart Libertarian', if you think about it, is 'in and of itself' actually a subtle contextual ad hominem and 'poisoning the well' attack on 'actual' (i.e. non-force-advocating) libertarians ... the only way it makes sense to prefix the "bleeding heart" adjective at all is if you're sneaking in a sort of suckerpunch claim that your opponents ('normal' libertarians who presumably, we are to take it, don't have 'bleeding hearts') are 'heartless'; it is essentially a claim that much pain and suffering would be allowed and ignored if 'ordinary' 'non-bleeding-heart' libertarians were ever in charge - it automatically frames all subsequent discourse and debate within this mindset, and it's 'smart' but sneaky in that it puts debate opponents immediately on the back-foot, as they must then sprawl to try defend themselves against a veiled implication that they're 'heartless', instead of arguing some point at hand, even before any rational debate has begun. It's a disarming tactic, in that debate opponents can't even counter-argue without automatically, by implication, being placed in a sort of 'you're heartless' spotlight.
It's a variation of the Race Card - e.g. if I called my blog "Thoughts from a non-racist libertarian", then it would subtly cast aspersions of racism on anyone who argued with my points (while also stigmatizing libertarians via association with racism). No truly honest intellectual discourse could take place in such a context.
Why can't "BHL's" (or 'left-libertarians') simply use reason to make their point, without resorting to such 'psychological-manipulation tactics'?