You say they shouldn't do it, then give a very detailed cleaning procedure... confusing!
I say go for itso long as the rocks or what have you aren't sharp. Even then some can be sanded down. Depending on the items will depend on the cleaning method. Woods should be baked, as previously mentioned. Stones and whatnot can be bleached.
It is the live plants and things that you really need to watch out for, as some can be dangerous to your snake's health. But again as mentioned, whatever items you introduce, make *sure* they are cleaned thorough as to not introduce harmful bacteria or whatnot.
All the best!