Showering and changing clothes before entering your facility isn't realistic for most visitors (auditors, investors, police).
The next best option is to cover them head-to-toe with hairnets, Tyvek suits, nylon gloves, and booties.
The risk is that visitors can carry potential pathogens on their bodies, clothes, and shoes.
By allowing them unfettered access to your grow site, they essentially hand-deliver mold spores and insects right onto your plants.
One of the main tenets of Integrated Pest Management is to restrict the entry of potential threats into your facility. The constant introduction of new threats can thwart preventative insect and disease efforts.
Don't let people walk around your facility in the same clothes they have on when they arrive.
Most commercial indoor grow sites have showers and work uniforms for frequent visitors.
For everyone else… if you can't wash it off, cover it up!