Consider adding a robots.txt disallow line for the add_to_wishlist URLs

[garyillyes]

While there's already a rel=nofollow added to all Add to Wishlist buttons and noindex otherwise, the same URLs can be discovered by crawlers elsewhere on the site or offsite, without the nofollow attribute. This causes problem for some sites because crawlers discover those URLs and, in some cases, crawl a few million of the add_to_wishlist URLs before realizing they're useless.

If possible, consider injecting a new rule in the robots.txt of the sites that use the plugin to generally disallow crawling of these URLs. Something like:

disallow: /*add_to_wishlist