ido-work-directory-list-ignore-regexps

ido-work-directory-list-ignore-regexps is a variable defined in `ido.el'.
Its value is

nil

Documentation:
List of regexps matching directories which should not be recorded.
Directory names matched by one of the regexps in this list are not inserted in
the `ido-work-directory-list' list.

You can customize this variable.