Web evaluations have two basic parts: on-site evaluation and off-site evaluation.

On-Site Evaluation

Website

Test to see if the website is responsive by shrinking the size of your browser window. If the site does not change to fit the smaller screen size, it is not responsive. An older style mobile website may load only on devices, but will not adapt to the smaller screen size. Google prefers responsive sites because it reduces duplication.
Test what CMS (content management system) the website is built in using http://guess.scritch.org/

On-site SEO

Check your title tags, meta descriptions & heading tags. You can do this by viewing the source code, or alternatively by downloading the SEO toolbar and using the “SEO X-Ray” tool which looks like a big red X when installed. The SEO X-Ray tool only works in Firefox at this time. You’ll need to sign up with an email address here to get it for free: http://www.seobook.com/free-account/

If your titles, meta descriptions & heading tags have keywords and geos that target a clear target (ie: AC Repair Chicago) you can attempt to determine the campaign target by this and assume that someone is performing SEO in some capacity.
If they have items like “Home” or just simply the brand name, you can assume that no one is performing SEO at this time.

If you were able to determine the primary target(s) in the last step, start a new private window to prevent caching impacting results, make sure that you’re logged out of all Google accounts and try some primary searches to see how well the website ranks for those terms. I’d recommend trying a half dozen primary terms such as: AC Repair, AC Service, AC Installation, Heating Repair, Heating Service, Heating Installation. Make sure to add the location (like Heating Repair Chicago or Heating Repair Chicago, IL) dependent on what you found in the previous steps.

Off-site SEO

Check your domain authority & page authority using a tool like this and record: http://www.seoreviewtools.com/website-authority-checker/

Summary

In summary, your web evaluation should be concise but provide the information you need to start the discussion. Remember that things you discover in a web evaluation may be inaccurate due to the dealer having hidden pages, multiple domains, or even hiring an SEO company that simply isn’t doing their job.

A sample web evaluation would look as follows for a site like http://www.alltemp.com/:

Web: Modern, responsive WordPress site. Strong use of headings. Good mobile design.
SEO: Targeting Chicago and other surrounding suburbs. Found many first page rankings for primary search terms. 35 PA, 22 DA.