The ultimate solution is never do merges from Ancestry, or anyone's database, online or otherwise. Add the data to your database, and create your own sources,citations and repositories.
When you merge you add a lot of sources, some legitimate and some not. The bottom line is any time saved by using the Merge, will be more than be offset by the time needed to clean up your sources, and remove those that are questionable.
About 10 years ago when I was new to genealogical software I did some merges. I am still finding some of those bad sources, after I spent several days about 3 years ago going through my database and removing questionable sources.