Star emissions seem to be the biggest eye sore for me. From afar you think its a nebula and then zoom in to see this.

It doesnt take much to clean it up. I did the next picture in about 10 minutes with PSP.

Of course, not all background stars, etc are placed back in the right spots. Would need a true expert to get that part right. But it would be a lot nicer to see them cleaned up a bit.