Depends on what service you provide. If you add the for-profit angle to HEALTH CARE or RUNNING water, suddenly having a multinational vacuum cleaning the people' s pockets to take their profits overseas is not a very good idea, or is it?
How good was the California electric market deregulation with ENRON? ... I suggest you watch "the smartest guys in the room".
Some things shouldn' t be in the hands of the for-profit private sector, specially when we' re talking about a natural monopoly or serving the whole of the population, including the ones that can' t afford it.
FC