Laurent Bossavit explains the notion of "Cargo Cult" programming - the example being setting a temporary variable to null (i.e., one that is going out of scope)
You may object that the setting-to-null superstition is totally harmless. So is throwing salt over your shoulder. While this may be true of one particular superstition, I would be particularly concerned about a team which had many such habits, just like you wouldn't want to trust much of importance your batty old aunt who avoids stepping on cracks, stays home on Fridays, crosses herself on seeing a black cat, but always sends you candy for Christmas.
What superstitious coding practices does your group have?