Use a good strong glue to bind a strip of the HOOK onto the back of the wallet. The soft, fuzzy loop material won't be uncomfortable, particularly if you face it away from your body. Now, when you slide the wallet into your pocket, the Velcro strips mate. The only difference in the manufactured wallets is that the HOOK is stitched on instead of glued. It is possible to walk around late at night and never feel threatened.
Property crime is more common, and thefts of or from autos seems to be a Bulgarian specialty.
In downtown, people are pretty much jaded towards visiting foreigners. Many people are merely indifferent. But if you go anywhere smaller, especially the places that Bulgarians think tourists should see, you'll find a lot of people who are still fascinated that an American is kicking around in their country. While walking in the city, be mindful that although there are pedestrian crosswalks, there are also pedestrian tunnels at or quite near every major intersection. As a bonus, many of these tunnels also are the location for some quite wonderful shops, cafes and other attractions.