http://www.w3.org/mid/B6CB855C5769484F862F4FB2CCFA50F402D545A7@VHAISHMSGJ2.vha.med.va.gov

Guidance for conformance checkers

Allowing a conformance checker to allow images without alt attributes as
long as they have a title attribute are asking for trouble.  Already,
people assume that title and alt can serve the same purpose, and
although the spec explains the limited situations in which a title
attribute is acceptable, your average web-developer is not going to read
the specification.  We have not gotten web devs to reliably implement
alt attributes yet, allowing conformance checkers to pass an alt-free
img because it has a title attribute, or because the image has been
generated with certain tools, will only maintain the level of "but the
checker said it was fine" that we already have.  Images without alt
attributes should always be flagged. If exceptions need to be made for
the cases listed in the situations cited, those exceptions should be
made knowingly by a human being somewhere (webmaster, site maintainer,
etc.).  Also, with the advancing level of image recognition, there may
eventually be automatic ways of generating rudimentary alternative text
which could also count as rudimentary keyword generation for
categorizing online images.  Explicitly excusing a condition based on
current inconvenience and limitations seems short-sighted.

It would also be useful to have a way to view alternative text even if
images are not turned off, for users who would benefit from this
feature.

PS. The suggested alternative text for the image taken by the blind
photographer would seem to be inaccurate.  Hummingbird feeders do not
contain nuts and seeds, they contain sugar water, so whomever described
the picture as a hummingbird feeder has mislead the alt-text reader.

[split out from bug 13590]