On Twitter, Google’s John Mueller was asked how Google looked for rich snippet spam. According to John Mueller, Google detects rich snippet spam through algorithms and manual spam reports:
@davebuts Yes, pretty much all of the them.— John Mueller (@JohnMu) 4. November 2015
In general, it is not a good idea to spam Google. Sooner or later, Google’s algorithms will find the spam, or your competitors will report your site. Better use white-hat SEO methods to promote your website.