I think the questions of ethics are insurmountable.

"The blogger writes:"Remember, these are just some goodies for listening purpose. If you like it, buy it." That's just what many of us do (and some argue that free mp3 distribution increases record sales) but I'm sure there are lots of freeloaders"

I'd say you being hugely over-generous here. The emphasis is the other way round. There is a tiny handful of consumers who buy albums after they have [illegally] downloaded them; the vast majority are freeloaders.

If the albums being put up were only ever long-deleted, long-out-of-print albums, then the practice might be defensible. But that's rarely the case. And even then, it scuppers any plans a record label might have of re-releasing those albums in future. And anyway, I don't ever see any attempts to actually reimburse the musicians responsible for those albums.

That's my biggest gripe about those blogs. For all their talk about "bringing back lost classics of folk/blues/whatever" they never bother to try to contact the musicians that made them. Do they ever volunteer to set up Paypal accounts for these musicians, so that users of those blogs could donate money to them? Do they care about whether these musicians are earning any money from the music they so gluttonously consume? Do they give a toss whether these musicians are alive or dead?

Essentially, such sites are entirely about passive consumption. You don't even read any good criticism on those sites: check out the comments and responses on those blogs and it's always "Thanks! What a great album! Now put up everything else they ever recorded!"

Music blogs are the ne plus ultra of music-reduced-to-pure-commodity, music-as-entirely-passive-consumption.