what exactly? What metrics can you show that prove out how successful you were? How many new members signed up? How many people contacted you or the club afterwards?

As Archie posted very eloquently: the results of his and Brenda's efforts weren't worth the effort.

I would love to get a de-brief after the show to understand what actual results are for being at a show. How many new members?

In business we say: sometimes the juice isn't worth the squeeze.