Upload & Sell: On
Hey, I actually bought a 24-70 a long time ago on ebay with the same issue you have now. The end was bent in so that means no filter could be used. I didn't know before I bought it, but they gave me some cash back. The glass was perfect. The kicker was that the seller took a wrench to bend it back. You could even see the teeth marks from the wrench, which bent in all the threading.
Anyway, I used it as is, like others said, if it ain't broke, don't fix it. You can always use a hood.
Eventually the lens went haywire on me. There was lots of lens creep, the zoom ring was very loose, and the final straw was that it wouldn't AF other than at 24mm. So I signed up for CPS gold to get the 2 free clean and checks and used one on the lens. Surprisingly, they fixed everything! It was like a new lens. Shocker?...no charge!
Not bad for a $600 bent up lens which I ended up using for 3 years and selling a few weeks ago for $1150. Granted, this was the NJ repair facility. I hear they are just about the best.