I wonder about the marketing and creative strategy that went into creating her site. If she's getting traffic from AdWords and not getting leads, then it seems to me that she may need a newly designed web site rather than
SEO. I am often contacted by prospective clients who don't know the difference between
SEO and design, so it's quite possible that she contracted for
SEO when she really needed a redesign to improve lead conversion.
I agree that neither editing with Dreamweaver or invalid code should be detrimental to
SEO. I know plenty of invalid, tables-based sites with page 1 Google SERPs.