Most stamps issued today by the worlds postal services are for collectors and yet I see no mention of these.
In the UK, just about every issue is for collectors and will never be found in a post Office.
The issues talked about on the website linked to in the initial post are bogus and have been around for years, nothing new. I agree with khj, collect what you like.
Recently, Internet auction site Delcampe have cracked down on these type of issues and have warned sellers to list them in a new section for these 'types' or be banned.
I had a quick look around the PWO website and at random I clicked on Chad. What a laugh that was !

I found a letter from the Chadian Authorities to the UPU complaining about illegal issues and there was a part-list of the items they were concerned about. That is fine.
But on the other hand, Chad is/was

notorious for excessive issuing policies purely to raise finds from collectors. Is that OK ?
Finally, and I know I have said before on SCF many times, SG SoTW catalogues list an 'Appendix' after some nations listings and state:
"The following stamps have either been issued in excess of postal needs or have not been available to the public in reasonable quantities at face value".
A sadly hypocritcal statement in this day and age when most stamps are issued for collectors and are most definitely not readily available !
Londonbus1