Подскажите, люди добрые, что имеется в виду?

я б писала обиняками, типа ...только убедившись, что ее персонаж - хорошая, душевная девушка...

"Mean" = (1) small; (2) cruel; (3) ignoble; (4) stingy; or (5) average.
Readers today often misunderstand sense 1, believing that a "mean-spirited" person is malevolent, evil, or malicious -- e.g.: "His stunts ranged from sophomoric -- punching holes in Styrofoam coffee cups -- to mean-spirited [read 'malicious'] -- calling up the wives of fellow cops and in an uncannily realistic feminine voice pretending to be their husband's mistress." Todd Lighty, "Former Cop Crossed Line, Destroyed It," Chicago Trib., 19 Jan. 2003, News §, at 18.
Actually, a "mean-spirited" person merely has a small spirit, a petty mind -- e.g.: "Yet, more and more, voyeuristic, fundamentally mean-spirited shows like this appear to be the wave of the future in TV. Say it ain't so, Joe." Noel Houston, "This 'Joe' Ain't Shoeless, Just Soulless," Newsday (N.Y.), 20 Jan. 2003, at B2 (отсюда: http://www.amazon.com/Garners-Modern-American-Usage-Garner/dp/0195161912)