yep, as soon as you start talking about SERP, PR, on-page, off-page, whatever, the clients eyes gloss over and they lose interest.
the best way to sell SEO to clients is to just do it and not give them a BS spiel, which will more often than not go over their head. it's like talking to the client about html/css/js or the benefits of the chosen CMS, they simply don't care, otherwise they'd do it themselves. its your job as the developer/designer to "just do it"...
at the end of the day they don't actually want to have to have their head filled with this jargon, all they want to know is that their business will be successful. show them this through results.
