How can you tell the difference between prejudicial and nonprejudical.

Question

prejudicial - "leading to premature judgment or unwarranted opinion ".
Anything which leads influencing other toward one side of an argument is prejudicial.
Statements of opinion are prejudicial. Statements of established fact are not.

You can also analyze writing as to an inbalance between positive and negative terms about a particular topic, especially adjectives. This is more likely prejudicial, if there is no data to support the staements.

Although I seem to be re-stating what GuruBlue has already said, you might get more out of this article, http://www.members.cox.net/dagershaw/lol/Prejudice.html.

I hope this helps a little more. Thanksfor asking.