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User agent strings: Spoof uniformly as Chrome+Windows or supply unique UA for each domain?
(links.hackliberty.org)
This is a most excellent place for technology news and articles.
The problem with a different spoof for each domain is that this behavior on its own can be used as a fingerprint based on timestamp and IP in access logs.
Hiding among the crowd is probably better, especially since newer versions of Chrome all report the same UA you blend in even more.