How Google’s Mobile-Friendly Site Tester works

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Michael Martinez: Well, I get fairly consistent but inaccurate results when I submit sites to it. The tool has problems with 3rd-party scripts and small image files. Could it be that you`re serving dynamic content via Javascript widgets? Perhaps a slideshow or something that changes content?
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  Jay Lo: Thank you Michael, I don`t think they use js to insert those resources becasue I can see them all in the source code using . However, they upload those images to WordPress and put absolute path to the src value, is how it go wrong?
  
  Also, according to Google’s Mobile-Friendly Site Tester, the Googlebot-smartphone can`t load them, so even it works properly for the users, do you think this will be a problem for SEO?
  
  Thank you Michael :)
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  Michael Martinez: Hard to say. Have you tried Fetch and Render in Google Search Console? If you see the page properly loaded there, I think the site will be okay. Absolute paths to images should be fine. Still, I`ve never had the tester complain about not being able to load images. Does it say what the problem may be? Perhaps the uploads directory is blocked?
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  Jay Lo: Thanks, they are fine in the GCS.
  
  So I think that the resources being said unable to load in GSC are the real problems.
  
  Thank you so much !
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  Doc Sheldon: Sometimes I see results vary widely from one test to another, as well. I have seen that most often when deferred loading was in play. I`ve also seen that Google seems to be "moody" about if/when it bothers to look at JS.
  Like Michael, I don`t see image loading issues, if uploads is blocked, I would think that might be an issue. But it should be consistent.
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  Noah Lopata: Use GTMetrix as well, they provide a better breakdown
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  Jay Lo: Thank you Noah, just run it with GTMetrix, super detail !!!