"Harry K" wrote

The whole thing sounds dubious to me. Why would a contractor be
delivering a pile of ply if they haven't even started the tear-off
yet. It costs money and time to deliver and then remove uneeded
material

Appearances can be deceiving. They definatley arrived with sheets of
plywood at my place. Why? Because inspection already showed they would need
some. The company I used does enough roof work to have a ready stock on
hand so they brought what they thought they would need, then a few extra
'incase' (which we needed some of those few extra).

I would not deal, or even talk, to a "contractor' that "happened to be
in the area". Well maybe I would depending on the looks of the
equipment and crew but it would only be to get a bid for comparing to
other companies.

Always get multiple estimates but getting to see them at work on a neighbors
house can give you a good idea of the work they do.

I would say one other thing. A contractor who does too many different types
of jobs (all with one team) tends to not be very good at any of them. The
fellow we used does roofs (has a special team for that), siding (has a
separate special team), and custom windows (with a 3rd team). Each 'team'
does just their own type of work and do it well.