Truth be told, flat wound strings are the most prone to defective strings. The two most common defects are bad intonation or excessive buzzing. Regarding intonation, the question is "are you unable to get the string to intonate within the range of your bridge adjustment?". If the answer to that is "yes", the string is defective. If it just requires a significant readjustment from your previous string, that is probably OK and normal.
A defective string due to buzzing will buzz everywhere, usually not on just a specific fret.