Skype: lack of privacy and proof its services are insecure?

These articles indicate Skype can and does decrypt its IM traffic, albeit selectively.

So privacy is not guaranteed as advertised. From Skype's website
Nobody’s listening in.When it comes to talking, instant messaging or transferring files, we’ve gone to great lengths to make it secure. Skype automatically encrypts everything before sending it through the internet. Likewise, on arrival everything is decrypted on-the-spot and presented as crystal clear speak, text or a file transfer nobody can intercept.

Conclusions?

Skype is not up front about its real capabilities of decrypting IM traffic and attempts to mislead people with statements on its website. It does decrypt and apply filters to a self-selected set of its global IM traffic. This causes a lack of confidence in its promises of privacy in its IM services, and also raises credible doubts over its voice services too.