I agree totally with Stan. I don't have a camo on my 300mm f4, but I do on my Sigma 50-500mm OS. I don't believe it necessarily helps in the disguise application, but I bought it principally to protect the lens. Extended to full zoom the Sigma can easily be bumped or scratched and that why I bought it. The 300mm f4 can be carried in a deep holster bag so I didn't feel I needed protection.
Perhaps the problem is more of an issue with Canon users as the lenses are white, or even the Nikon white lenses.