You ask a hard question. I run into the problem all the time of 90% to 95% of the data included in a particular Webhint is correct and the rest is incorrect. What is one to do?
First of all, your question is specific to ancestry's WebHints. If instead it were for FamilySearch's WebHints, I'm not sure that my answer would be exactly the same because the hints work very differently for the two systems. Because of the specificity of your question, I will answer only for ancestry.
The first thing to understand is that strictly speaking, there is no such thing as WebHints in RM for ancestry. What there is are shaky leaves in ancestry. You can manually type in a new tree into ancestry and as soon as you get far enough into the past with your tree to start matching with other people on the ancestry site, some of the people you typed in will start showing shaky leaves. You can approve or reject these shaky leaves. These shaky leaves are hints that can be 100% right, 0% right, or somewhere in between.
With RM's TreeShare, it creates your tree on ancestry for you based on what is already in RM. Or if you already have a tree on ancestry, it copies the tree for you to a new and empty RM database. Either way, RM shows you the shaky leaves on ancestry within the RM user interface and it calls them WebHints. RM doesn't have any WebHints of its own.
That being said, I tend to want to process and dismiss the hints when I see them, rather than leaving them dangling forever. The only two ways to do so are to approve the hint or reject the hint. This is just me and it may not be right for you, but I tend to approve such hints if they clearly are the correct person and even if the data is not is not 100% correct. I will often make attempts to contact the person with the incorrect data to notify them the situation.
But I never, never, never bring any data from WebHints into RM automatically. I type everything into RM manually. So my approval of an ancestry WebHint does not have any adverse impact on my RM database. My rationale for this approach is that I can see an approved hint again if I want to do so, and the best I can tell I can never see a rejected hint again. There is no way that I know of to get it back. If you use TreeShare to bring data back into RM automatically, you surely would not want to being any incorrect data back into RM automatically, so my approach might not work for you. You might want to reject the partially incorrect WebHints.
This is just my approach. It is surely not the only reasonable approach and it surely won't meet the needs of everybody. But it does seem to work for me. I'll end by saying that in reality, the ancestry WebHints that are for other trees are much less reliable and much less important than the ancestry WebHints for records. Those records are what you really want. I sometimes wish TreeShare had an option to show only the hints for records and not to show the hints for other trees. But ancestry really wants you to hook up with the trees because (as their TV commercials like to say), that's the way you can complete your family history very easily in only a few minutes (even it's completely wrong!). I find the hints for trees to be a good way to hook up with other researchers who are working on the same families that I am, even if I don't blindly copy their data.