Is Francesca supposed to be evil?

Sinners are easy to control. The ferryman used her to score another soul.

I think she was also 'evil' as she made out with Ferriman ( as if they were in cahoots - or so she thought) before he killed her.

She was clearly evil as seen in the ghostly flashback murder/betrayal montage where she is shown conspiring with one of the murderous criminals before killing him, only to be killed herself by Quinn from Dexter

she was "in" with the double-cross.. before it turned into a triple-cross.

and eventually a quadruple-cross