I have big snarly-looking dogs usually.   And a small red sign on each
side of the van saying "Beware of Dog" because I sometimes have to park in
a supermarket lot or elsewhere where people might walk right past or get
into a car parked beside the van....and Max didn't like that...
He was about 110lbs with bright yellow eyes (Chesapeake retriever)  and was
not very friendly looking to anyone coming near HIS van... He's gone, but
we have another, a bit less protective but again with yellow eyes and a
pretty hungry look for anyone looking into the van.
   It's amazing how many people ask me..."Do you have a dog in there?"
Where is the dog? like that...The signs do get seen....and shoppers aren't
quite so likely to be startled and toss up their grocery bags and ____
their drawers when they are 'greeted' as they approach my van...
   I had another friend with a bay westie parked in New York city
normally....He had "Ernst's Reptile Show" signs on his van and it was
avoided also...