I have contacted a few people about errors on their trees, with varying responses. Some have sent thanks, and made the corrections, while others ignore the corrections, although at least one sent thanks! I have now begun to add comments to some of these trees, so at least anyone looking at them in the future might spot the error!
I would be glad to hear from anyone spotting errors on my tree, although it has only happened once, and I made the correction straightaway. I do try to note where information is unconfirmed, or leave it off completely, while keeping a note of it in my paper files.
The most recent comment I added was because I could not find a way to contact the owner - might that be because their subscription has lapsed? They had included a marriage which at first sight looked right, but had in fact confused an aunt and niece who had the same first name and middle initial. Since the GRO only gave middle initial the confusion was understandable, I had identified it from the county BMDs which are thankfully online. The aunt was the 12th of 15 children, while the niece was the daughter of the 2nd eldest, so the relative ages made the marriage a possibility for either.