Pluto has been in continous existence for more than 6½ years, and I want to keep Pluto going for a long time. Therefore, if you see Pluto in a cache, pick him up. It doesn't matter where you are from or where you are going. Pluto can go anywhere in the world. Pluto particularly enjoys international trips, and has been to Germany, Great Britain, France, Mexico, and the Bahamas and back to the USA.
It is great to put Pluto in most caches, and remote, challenging caches are fine, since Pluto is a strong, adventurous dude. Pluto, however, wants to be safe and secure, so don't put Pluto in a highly-exposed cache that is likely to become lost or stolen, such as one under shrubbery in a park or greenbelt. Also, Pluto doesn't like "travel bug hotels" because many such caches are not secure, so please don't put Pluto in a caches that appear to be "travel bug hotels" because many travel bugs become lost when placed in such caches.