Do post images distract from a sidebar opt-in form?

I am not sure with others and I am only speaking for my own experience but images are helpful. However, you should use images that have great quality and should have strong relevance to the post. It shouldn't be a large file so it won't slow down the loading of the site. You should also position it in a way that it doesn't steal all the spotlight.

Sorry, I have no evidence to offer: only a personal belief (which influences the design of the landing page of all my niche websites) that they might. I don't like to have too many images on that page, and I like the few I do have to be uniform in size and neatly aligned, so as not to present a cluttered, distracting page.

I suspect that the answer to this is going to depend a lot on one's traffic demographics. My productive, realistic traffic is mostly from article marketing. I don't care much about the SEO traffic - even though I get tons of it - because by comparison, I can't exactly get rich from those visitors, whatever I do. My important, profitable, article-derived traffic comprises visitors less "in need of images" than "the average visitor" (and more willing to read longer, less-broken-up text).

It may even depend on the niche, as well.

Not an easy thing to test, perhaps, but I think that would perhaps produce your only adequately well-informed and relevant answer. :confused:

Yes; I think they might well, and I err on the safe side. But I can't prove it, even for my own sites - much less for anyone else's.

(Recently, I also found this view expressed in one of Seth Godin's books, which was quite pleasing in a sense: I feel we're at least "in good company" in being concerned about this point, anyway!).