Why are the walls stained or bubbling?

That tide line of stains and blistered paint along the bottom meter of the wall is rising damp, and the wall is doing exactly what it was built to do. Marrakech sits on a shallow water table fed by Atlas snowmelt, and traditional walls — rammed earth, fired brick, lime plaster — are porous on purpose. They drink from the ground like a paper towel standing in a saucer. As the moisture evaporates from the surface, the salts it carried crystallize just under the paint, and the crystals push. Hence the bubbles.

The lovely irony is that modern repairs make it worse. Cement render and plastic paint seal the wall's face, so the water simply climbs higher looking for an exit — which is why you'll sometimes see a pristine ground floor and stains blooming at head height, like the wall is rolling its eyes. Lime breathes; cement suffocates. The old builders knew, which is why a wall re-limed every generation for four hundred years often looks better than one renovated in 1995.

So it isn't neglect, and it isn't a leak. It's the building's circulation, made visible. A well-kept riad simply re-plasters the lower walls on a cycle, the way one repaints a boat.