Find unworked tickets

We have many tickets that languish for sometime before we can process them,
and so they are changed to stalled in order to give a cleaner front
page. Consequently,
we cannot easily use the status to determine whether or not there has been any
action on a ticket. Is there some way (not seen anything on wiki or list, nor in
Query Builder/Tools>Reports) to find tickets without comments/replies?

Thanks in advance,

Jerrad

Cambridge Energy Alliance: Save money. Save the planet.