OK, two problems with that statement.
1. Searching for keys you believe are associated with that program and manually deleting them will 9 time out of 10, NOT find all the keys that the program installs. Only a good reg cleaner will do it correctly.
2. Giving people whos skill level and knowledge you arent absolutly aware of, the advice to enter and edit the registry, is dangerous, foolish, and generally frowned upon by the IT industry. not everyone is as comfortable in the registry as some of us, and considering that making one wrong change in the registry, or deleting one thing by accident can destroy windows and require a complete restore, it is BAD advice to tell people to edit their registry when other options are available, and more reliable.
This is not an attack on you, just a friendly reminder to be sure the advice you give out is suitable for the person your giving it to.