There are a number of different steps to take when an employee lets his office go to the dogs, but you need to look at a few related issues before you pounce.
The first issue is whether the photos on the wall contradict your company's policies, values, or culture. There are some workplaces that are very casual on this matter, essentially turning them loose. The idea is to focus less on what goes on the walls, and more on what goes on within the walls. At the same time, there are companies that have strict policies that require approval before anything is placed on office walls.
If your workplace is on the stricter end of the continuum, you should meet with this employee and give him the facts. He's an adult, and he should be able to thin out the pack without too much trouble. At the same time, if your company is fairly permissive in terms of wall dÈcor, then you need to ask yourselves why you are so doggone upset over this matter.
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