I was wondering what happens if i place image ad formats on one of my pages but there are no advertisers utilizing image ads at a specific time. Say if i have this ad on a page optimized for Dog Travel, But then all the advertisers bidding on image ads for keywords related to dog travel are no longer utilizing image ads does this mean the ad will show charity ads? Or will it be replaced with contextual ads? Thanks.
Yup, PSAs or alternative color/ads if you point this to be the default behavior If you do: google_ad_type = "image" you won't be able to get text links in any way