Karen -- all it takes is something as simple as field labels aligned with fields using tables alone. Or, for that matter, any metadata (labelling, sectioning) not strongly associated with the intended content. A screen reader may parse the text in the correct order, but it's missing the association between the label and content, so it can't tell the user what field they're currently in and so on.
Admittedly, the better readers give it a valiant effort, but since there's no guarantee what the alignment between field and label, say, will look like, this is a hit-and-miss venture at best. That's the problem with relying on tables for layout -- the developer/designer tends to use them to the exclusion of semantically-oriented markup options. Visually-impaired users (like the rest of us) would also like options to quickly scan a page for relevant content. If markup is entirely presentation-based, that's really, really hard to do.
Karen -- all it takes is something as simple as field labels aligned with fields using tables alone. Or, for that matter, any metadata (labelling, sectioning) not strongly associated with the intended content. A screen reader may parse the text in the correct order, but it's missing the association between the label and content, so it can't tell the user what field they're currently in and so on.
Admittedly, the better readers give it a valiant effort, but since there's no guarantee what the alignment between field and label, say, will look like, this is a hit-and-miss venture at best. That's the problem with relying on tables for layout -- the developer/designer tends to use them to the exclusion of semantically-oriented markup options. Visually-impaired users (like the rest of us) would also like options to quickly scan a page for relevant content. If markup is entirely presentation-based, that's really, really hard to do.