If you are getting too many black marks from the council,
get a level two house, and make the tenants "The Punks".
After awhile they should start to complain about a hedge and will
give you black marks if you do not drastically decrease their
rent. Drastically decrease their rent, and you should get some
white marks. Then, put their rent back up again. Do this repeatedly
until you have no black marks remaining. Then, either replace
them, agree to their demands, or make them have children. If you
continue to do this, you will receive many white marks which can
be exchanged for cash (100 marks for $10,000).