Clearly, the landlord cannot automatically charge you for painting just because they automatically do it for each incoming tenant, however admirable that policy may be for new tenants. They can only charge for above-normal wear and tear, so if you left the walls with normal usage, you are entitled to no charges for painting.
That said, the key to happy tenant departures is whether the landlord insisted upon the beginning of the tenancy for a list of deficiencies upon moving in. That should come 1 – 2 weeks after move-in, so the tenant has a chance to note everything. I usually have to prod my newbies to provide it, but it comes in handy upon move-out to end arguments about pre-existing damage.
