Many factors are considered when making assignments. Acuity, nurse experience and skill, pt preference and continuity of care are some of the factors that influence a charge nurse's decision when making an assigment.
You can always ask the charge to double check the assignments if a question arises. Sometimes things get overlooked and a "fix" is neccessary.
Things that will make me turn

(ugly) include nurses who come in 20 min. late and start picking the board apart. Those nurses who refuse to do charge but want to tell everyone else how it should be done. When the board is not current at change of shift.