I know a Googlewhack only returns one result but what if....

[Mojo-Jo-Jo]

...your search returns no results.
Is there a name for that and is it rare?
Are there any criteria for it to be valid?

[Mojo-Jo-Jo]

Oooo. I've found one. I like the name.

[ChuckFickens]

A googlewhack is impressive if you can find a proper one.

A search that returns no results is probably gobbledygook...

"hgjegjnldfnfbjknvka" returns no results.

[ChuckFickens]

Although it will probably return one result now I've posted it....

[Old_Geezer]

:-) I was going to say a misspelling.

(Although these days you're likely to get one of those annoying, "did you mean", and the results from that.)