I have a tapered reamer for Chevy TRE's and it has been passed around my club like a $2 hooker. The flutes are not sharp anymore and it wont cut, no matter how much pressure I put on it. It is kosher to take a small file to the dulled area? I dont really want to buy a new reamer as I only need to do one hole so would this be ok or will I crash into an orphanage full of puppies?

It's worth a shot, but I would think it would need to be ground to keep the proper flute geometry. Have you called around for quotes on sharpening yet? There's a ton of places here in Houston that do sharpening/grinding. It may/may not be worth it though vs. buying a new one. Out of curiosity I called a shop just now and they quoted $65.

Whenever you get it figured out let me know so I can borrow it next.:D

Use a small stone perpendicular to the outside edge. The cutting edge is the surface that is on the inside surface, not the outside surface. Depending upon your stock of stones and skill, you should be able to get a decent finish with a simple whetstone.

Stone it or take it to a tool maker for an edge.

A new reamer is ~$60 so I'm not gonna fuck with taking it somewhere to get done. I'll take a whack at it with my wetstone. It cant get any more useless than it already is so why not.

You do not want to do anything to the outside edge. The way it is sharpened is by grinding the inside of the flutes till a sharp cutting edge is achieved. If you mess with the outside edge you will loose size, taper, and cutting geometry. Send it out to a tool sharpener or buy a new one.

Any tool grinder/sharpener should charge less than 10 bucks to do it right.