There was a phrase I learned in living in DC ‘A crack whore turning tricks’. At the time, DC faced a wave of crack cocaine.
More broadly, it is a metaphor for doing anything for money, with no regard for public dignity.
For lobbyists, it is people doing anything to advance their cause and doing it in public.
If people want to game the system, it is often best to do it in quiet and out of the public gaze. There is no need to advertise your actions. After all, the chances that officials and others will learn of your actions is a near certainty.
Discretion, civility and human dignity are harder codes to work by but are more effective.