i want to re-paint the walls inside my old apartment. the walls are hollow tile concrete blocks that are painted already. before i re-paint the walls, i want to smooth out the surface to cover the ugly concrete block gaps and lines. i am not a handy-man and i just want to do this as simple as possible. i was told to use 'all-purpose spackling paste', but my concern is that spackling paste may not work on concrete blocks with painted surface. another suggestion is to use 'mortar mix' and the 'bonding adhesive', but this is a lot of work with all the dust and dirt. putting the dry walls to cover the concrete block walls is too complicated for me. what is your simple and easy suggestion to make the walls smooth and flat before i re-paint them?