wheel - 3:56 pm on Aug 12, 2010 (gmt 0)
My thoughts are that I wouldn't worry about hotlinking until it becomes a load issue. Now that it actually is a load issue for you, I'd clean the problem up pronto, and permanently. Fix it right once and be done.
I've read some pretty interesting things to do with hotlinkers through the years, one that comes to mind is substituing another image.