Many measures have been implemented to reduce the effect of bots, such as the 50/50 reward distribution, proper muting, blacklists, curation efforts, free downvotes, etc.

Steemcleaners lost its Steemit funding, so I'm not very aware of what will be done to combat spammers, scammers, phishers, etc., but I'm sure we'll find a solution together in the future.