Are iframes bad for accessibility?
Iframes pose fewer accessibility issues, though require additional work and management of multiple pages. Frames and iframes should not typically be used for presentation or display, but for content management (iframes work great for advertising and display of content external to your own web site).
Can screen readers read iFrame?
In general, iFrames are accessible on a screen reader, but a TITLE for the iFrame is recommended. See example of a Google Form iFrame below.