IMO if you are improving the robustness of scripts that have not been "developed" but rather "evolved" then theres a reasonable chance the authors will appreciate it, either becuase they never found the time or inclination to do the cleanup, or because they just arent that good at it. Ive known a number of people without strong development backgrounds who couldnt refactor to save their life, but were extremely appreciative when somebody helped them refactor their code.

On the other hand, sometimes people without strong backgrounds in development will not appreciate the changes. Most likely these people wont understand the criteria that you have used to refactor the scripts and won't see any benefit in the changes and may even see it as a personal slight. People like that will always be a pain to deal with so i wouldnt worry too much about them. Just be friendly and not cocky and it should work out ok.