HDOP NMEA filter level

Having looked at some of my (not yet uploaded) tracks, I have a bunch of clusters of points where I have been indoors, and times when i have had poor signal quality etc to the point that that particular part of the track is worthless.

I would like to discard this data before inflicting it on the community.

I believe that filtering the data by HDOP is the best way to go, however I’m not sure where to set the filter limit to – varius estemates so far range form 10 down to 4.

Ideas? Sugestions? Alternatives?