<p>^^^If you doubt another poster’s veracity, you can bring it to their attention in a non-confrontational manner. You would do that by just saying so, and not quizzing them to make them prove something. You also negated what another poster said (maybe not intentionally) by your method.</p>
<p>Also, I think when somebody is a poster for whom English is obviously not their primary language you take into consideration that what they are saying may not be what they are intending to say (because of lack of familiarity with the language), so you cut them some slack.</p>