List bugs related to the geoprocessing commands at the bottom of the online ArcGIS help. If something doesn't work then when why not acknowledge it? I can't tell you how many staff DAYS I've wasted since 8.3 trying to do things that don't work only to find out later that there is a known bug!
There was on geoprocessing method in 9.1 that NEVER worked. The 9.1 online help should have mentioned this so myself and others wouldn't waste our time trying to make it work.