Today I edited an article featuring a pharmacy that offers its customers, among other things “qualified advice”.
Qualified has developed two almost opposite meanings, for reasons none of the dictionaries I’ve looked at explains: “1a) officially recognised as being trained to perform a particular job; certified; 1b) competent or knowledgeable; capable” and “2) not complete or absolute; limited.” (Oxford Living Dictionaries Online)
A qualified pharmacist would usually give unqualified advice, while an unqualified assistant would give, at best (or at least), qualified advice.
I assume that the advice given in this pharmacy is “of or pertaining to someone who is qualified”. I can’t really change it to “this pharmacy offers unqualified advice”.
Google Ngrams shows that qualified advice (in whatever meaning(s)) is more common than unqualified advice, while unqualified opinion (likewise) is more common than qualified opinion.