&gt; The most common &quot;why didn&#x27;t you select me?&quot; follow up answer I got was &quot;we need someone who is an expert in XYZ language.&quot; Sometimes it was even that they need someone who is an expert in ABC library (when I was already pretty-much an expert in the language.)<p>There&#x27;s nothing really wrong with that as long as they advertise such and make it clear before even starting the interview process that you won&#x27;t be hired unless you&#x27;re a library ABC or language XYZ expert.  The problem comes when they don&#x27;t advertise that, bring you in anyway, and waste everybody&#x27;s time.