Tell you what all mighty, give me and everyone else using our spare cpu cycles $1 a month and we'll stop? No? not a good deal?
If the added load on the CPUs cost more than they rake in, they are losing you money not gaining money, so unless you are just making sure you get the max electricity your rent includes, or are stealing the use of other people's CPUs, it is not always economical to run the CPUs mining something compared to letting them idle.
It was economical CPU mining BBQcoin for a year or so, and possibly might turn out to to have been CPU mining Tenebrix and Fairbrix, but most coins using CPUs on them is a net loss.
-MarkM-