Graffiti Gone...NOT!

So the theory is, if you cover over graffiti quickly it discourages the tagger from repeating in that area. Sounds fine in theory, but what if the person who covers it over, carefully paints it out so it is still identifiable, as in these two shots from QEH. They are clearly SAME and HEU5. Several questions arise, such as have these guys been discouraged by this action?, and is the school just running low on beige paint, but reluctant to re-order as red paint will be needed at the new school next year?