/who all [some words NEVER work, why?]

[Portasaurus]

Depending on what I am searching for, when I try to do a /who all X, sometimes I will get results, and other times I will just get "There are no players in Everquest who match those filters" even though there totally are players in Everquest who match those filters!

Examples of some that seem to NEVER work:

/who all unreliable

/who all port
/who all porta
(but /who all portas returns Portasaurus)

/who all ear
/who all eart
/who all earth
(but /who all earthr returns Earthra*)

Is there some special reserved-word list that you are not allowed to use in the /who?

*Earthra is not me, just some random person I found whose name seems to be affected by this.