When should I use HTML frames?

I have heard countless reasons on why not to use HTML frames, from their lack of accessibility, the general lacking in UX, their being completely inefficient/unmaintainable, or them just being outdated.

This all brings me to two questions:

1. Does this general consensus of hate apply to iframes as well?
2. In what scenario(s) is it acceptable to use frames/iframes in your code?