In that case, you can add an exception for the special (small, but legitimate) shop that you trust. A permanent exception will be set once and only once (per certificate lifetime of course).
I don't need to "trust" every single website, e.g. those I reach from a Google search. I intend to get in, read the info to see if that helps me, get out; I don't expect to get "cooties" just from loading a page (indeed I've been browsing the Web since 1992, before it could be used for any sort of attack, and *never* caught anything through a webpage). Now, having to do the "I Understand the Risks > Add Exception > Get certificate (huh?) > Confirm Security Exception" dance every time I want to read a message at a forum / mailing list archive becomes ANNOYING quickly.