Activist investor Starboard Value rattled Perrigo Co. on Monday with a scathing criticism of the drug company's management. A look at Perrigo's financials reveals one way management has excelled: Making its results look good.

Quarter after quarter, the Dublin, Ireland-based maker of generic drugs relied on one-time expenses and novel terms like “organic net sales” to highlight a string of profits on its own adjusted terms. In its full-year 2015 report, Perrigo listed $1.09 billion in adjusted profit. The word “loss” was used sparingly, despite a net loss of $33 million using non-adjusted accounting that adheres to Generally Accepted Accounting Principles, known as GAAP.

It was the biggest percentage disparity last year between adjusted and GAAP figures among companies in the Standard & Poor's 500 index, according to data compiled by Bloomberg.