The purpose of this thread was clearly stated by sjones in the 2nd post….
And people's views about who supposedly is and who supposedly is not qualified to express his opinion of a given artwork are, of course, a point central to this thread. That's partly because one poster commented that a photographer's work cannot be appreciated by anyone who does not know the concepts the photographer has been developing her entire career and partly because you quoted and linked a commentary in which it's said that no one should refer to an artwork as bad unless he can "lay claim to a high level of expertise."
I disagree on both counts, which some have characterized as an ignorant and uneducated position.
Everyone can make a comment but the key is which comments are valid…?
An individual's artistic preferences are not made valid or rendered invalid based on things such his "level of expertise," how many art-history books he has read, whether he knows that the artist has been developing a certain concept for a long time, or whether he regards himself as more educated than those with whom he disagrees.
"I like the works of Cindy Sherman" is no more or less a valid opinion than "I don't like the works of Cindy Sherman."
Yet again, financial considerations—speculating on whether certain works will increase in value and are therefore good investments—are a separate issue.