A registry entry with a path pointing to nowhere is not necessarily bad, but they're "convenient" for registry cleaners to call out as something scary and throw big red warning messages to entice purchases and help folks "feel better" about it when the scary warning messages go away.
I hate that too! Some of those programs really go overboard with those big red scary warnings, calling them "problems", when in fact, they are not. It is those tactics that often give all Registry cleaners a bad rap when in fact, they should not all be lumped together as "evil".
Even CCleaner lists "issues" it finds under a category heading called "Problems". But at least it goes on to define the problem/issue, lets you easily deselect it for fixing, and never reports a problem that requires some purchase to fix it as some programs do.
And it always prompts to backup the Registry before making any changes, and, at least in my own testing, restoring from that backup actually works.
While the debate rages on as to CCleaner's Registry Cleaner's benefits, if CCleaner were "evil" or destructive as some of those programs clearly are, it would not have become one of the most popular utilities and cleanup programs ever created, and maintained such popularity and reputation for over 10 years.