Could you please elaborate? Does something nasty happen to old plastic
pots?

or paphs, reusing
pots is probably not a horrible thing. For other genera, it is a good
way to spread virus if the pots aren't very well cleaned and
sterilized. So, for anything

The cost of plastic pots is so cheap that it makes no sense to reuse them and
take the chance that a virus may be transmitted. You also need to take into
account the cost of your labor, bleach and other cleaning aides. Afterall you
could be doing something else besides washing old pots.

My partner and I ran a commercial orchid nursery for about 15 years. If we got
a mail order for a plant we would be shipping bare root that had been potted 1
minute earlier we would still throw the pot out. This policy applied to all
genera.

Besides there are some who believe that even paphs can be affected by orchid
virus and most definately phrags.

Would you risk a $100 plant for a 5 cent pot?