Or, it's a case where they've sold a gazillion, and a "normal" rate of
return results in a big pile!

Most of the refurbs tend to be cheap low-end models- these will sell in
higher numbers, and even a normal failure rate will result in a good
number of available refurbs.  Add to that non-defective returns of "test-
drives" and that's a lot of refurbs for sale.

My refurb Cingular Nokia 3120b I bought a year ago was a steal at $30
with no commitment and is working fine unlocked with T-Mo prepaid
service.  I wanted a cheap, reliable, small 850/1900 phone as a backup
and the 3120b fit the biil. (At that time, T-Mo's entry-level was the
similarly priced and featured, but much larger, Nokia 6010.)

Another way is to look for the brand name "Motorola" on the phone.

Not necessarily.  Not so simple.  The availability of refurbs is normal
on high-volume products no matter how good they are; e.g.,
          Volume   Return Rate   Returns
Phone A   500,000        1%         5,000
Phone B    10,000       10%         1,000

Phone A is clearly more reliable than Phone B even though it has many
times the number of returns.  Thus what matters is the return rate, not
the number of returns.