One of my theories as to why the hash rate has seen a fairly sudden drop over the last week or so is that some of the botnets are moving on to other ventures/being caught etc.
Can't agree, I think that professional miners hopping, not botnets. Or maybe I don't know about some profitable cpu-mineable coins. I still believe that XMR is a miracle for CPUs so far.
As said just a theory. I guess in reality in regards to whether the coins are being sold straight away or held professional miners and botnets do mostly the same thing.
Exactly, miners usually mine and dump, it does not matter who and how.