I am simply wondering what is common etiquette and dress at most meetups such as these?

While I am sure it wasn't very funny to you at the time, I'd bet that a story about the yard of your rental being dug up in order to facilitate a mud wrestling showdown has to be a crowd favorite at parties.I am curious, though; did you make any attempt to recover the damages done to your property? 

When I did open up the siding, I did see damage that was not and could not have been pre-inspected without damaging the siding.  

Your outside A/C is usually the only thing to worry about, although they'll tear the coppper out of your walls and do $20k worth of damage for $20 in copper in some areas. 

Here is a picture of me beside a Cessna we chartered (admittedly, my friend decided to dress casual).

All that hot air and moisture running through the pipe for years is bound to do some damage.

I'm not an expert, but that would be a red flag for me if a seller won't allow for an inspection...especially with such extensive damage that would require 67K + in repairs.

I said they would need to sign an addendum to our lease to reference pets and the tenants responsibility for any damages caused by the pet and they had no issues.

As several have suggested, you will need to determine the exact nature of the code violation.Hopefully it is not a structural issue.As a structural engineer I have experience with evaluating structural damage and it can be quite expensive.

That is absolute fraud, I hate suing, but this seller should be sued to pay for damages