One issue with "a genuine, good-faith attempt at improving the properties" is that unlike single family homes, trailer homes are actually a depreciating asset.

One issue with "a genuine, good-faith attempt at improving the properties" is that unlike single family homes, trailer homes are actually a depreciating asset. A 30 year old trailer home isn't worth much since the cost to do meaningful improvements is likely more than the home is worth. This means an owner can only make a profit on the rent as opposed to a mix of rent and equity like most real estate. Trailer parks on the other hand are appreciating assets and is where the real money is made by renting plots of land to the trailer home owners or tenants.