WordPress Viagra hacks are difficult to detect because of the following reasons: 1. Hackers target high-ranking pages because they receive a lot of traffic. Or they target pages with high earning potential. The hack won’t be present across the entire website making it hard to detect especially if it’s a large website with dozens of posts and pages.   2. This type of hack is not visible to you, the website owner. Nor is it visible to direct visitors. It’s only visible to search engines like Google or Bing. Hackers are targeting organic visitors who are looking for pharmaceutical drugs like Viagra, Cialis, and Levitra on the search engine. 3. Hackers want to utilize your website for as long as possible so they take steps to ensure that remains hidden. They have developed ways of disguising malicious codes which is difficult to detect even for seasoned programmers. However, a good malware scanner can easily detect a pharma hack on your website ad help you clean it.