An interesting question about Twitter Cards

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

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  Kim Herrington: Have an interesting question!
  
  I've launched a new website and want to use Twitter cards. I noticed that when someone shares the homepage, the Twitter card for the page isn't an image I want shared. Someone noted that putting the image I want displayed as the last image on the page with a size of 0 px is a great way to workaround this issue as Twitter picks up the last image on the page.
  
  However, I'm a bit hesitant to "hide" an image in terms of SEO. Any thoughts on this or alternatives to fix this issue?
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  Bret Carmichael: I'm not an expert on this, and don't know much about Twitter cards. So, I suggest a second opinion. I don't think a hidden image will give you any SEO trouble. However, if you're also hiding alt tags with the image, that might hurt you. If I've misstated anything, I welcome correction from the community. 
• 
  Tony McCreath: You should use the markup Twitter uses. They provide instructions here: ;https://dev.twitter.com/docs/cards
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  Dave Elliott: what tony said really.....markup your page properly, verify it/submit to twitter(a pain it has to be said!) and twitter will almost certainly use the correct image. ;https://dev.twitter.com/docs/cards/validation/validator
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  Edwin Jonk: From the expert panel in this weeks SEO Questions hangout on air on 00:36:30 into the YouTube video: https://dumbseoquestions.com/q/an_interesting_question_about_twitter_cards +Kim Herrington
  
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• 
  Kim Herrington: I should have been more clear! Poorly written question on my part.
  
  I have validated the Twitter cards for the entire website. It's my understanding that to have images enabled on the cards, you have to enable the image for the entire site's Twitter cards (i.e. there is only one Twitter card setting for a domain). I want images enabled for the rest of the site, on blog posts for example, since that is an important part of my strategy. It's my understanding that means the Homepage Twitter card will display an image too.
  
  The problem is there isn't a visible image on the homepage that I want shared. There are images but they are of people who gave testimonials and images being pulled from blog posts. Since those blog images don't "exist" according to the markup since it's dynamic content, none of those can be used for the Twitter card image (As far as I know. I am not a coder!). The other images on the page aren't appropriate to be displayed since they're of people who aren't associated with the website other than former customers.
  
  The homepage layout doesn't have a good place for an image I'd want shared. If at all possible, I don't want to add a visible image to the page. I understand that this might be the only solution but I want to weigh out other options first.
  
  Someone recommended to put an image at the bottom of the page, use the Twitter markup for that image, but keep it at 0px so it doesn't display. As I said, I'm hesitant to use this technique because of search engines penalizing websites for other hidden content and question that this technique of hidden images might be something search engines don't like.
  
  I'm asking if the technique of using a 0px size will negatively affect my website's SEO. If anyone has ideas on how to have a different Twitter card setting for one page, that would also solve the problem. ;
  
  I should have been more clear on why I'm asking this question and apologize that I wasn't before. ;
  
  Thanks for those who have answered and for taking up my question in the hangout! +Bret Carmichael ;+Tony McCreath ;+Dave Elliott ;+Edwin Jonk ;