Investors really need to be on their toes to avoid being sucked into pro forma fantasy-land. Read the footnotes and question any pro forma numbers. Be sure to understand exactly what is and isn't included in the pro forma numbers. Companies have been using onetime charges to bury unfavorable expenses for years. Once again, I must caution that write-downs and charges are necessary and even good sometimes.
Chronic chargers are really the concern here.
Companies that use charges regularly to clear out the skeletons and hide management's missteps should be avoided. Often, expenses that would otherwise flow through the income statement lowering unadjusted net income are buried in these onetime charges. Charges can be a red flag for mismanaged companies. Spend some time looking for a pattern of chronic onetime charges. This is probably the most written about and at the same time, most brushed-off earnings distorter around.