Hardly whitewashed, and it might be worth pointing out that Galba took advantage of an existing breakdown in civil order that led to a senatorial decree that Nero was an enemy of the state, which meant anyone could legally kill him. Nero panicked, as he often did, and fled, eventually failing to commit suicide and commanding a slave to do it for him.
Nero had abused elite Roman sensibilities with his artistic career and publicity stunts. Worse still, he had used the patricians as a cash cow, blackmailing to leave everything in their will to him and commit suicide rather than punish their families. His popularity with the masses was affected due to episodes such as the murder of his mother - yet he retained a very loyal following nonetheless as the rebellion of a slave who happened to resemble him would later show.
Granted, Galba had already been given a death sentence by Nero and was effectively a rebel anyway, but Galba did not march on Rome until he had heard of Nero's death.