Gov. auction cars are nothing but repo cars in whose original purchase there was an involvement of a gov contract of some sort. My experience with them is good, but you do have to know what you're doing.
If you go the offline route, you should try to find as many auctions as possible in your local area. Go early, see what's available, who other attendees might be ( particularly dealers ) and how many of them there are. Study the rules, as they do tend to change a bit from one particular auction to the next. Always check the car and ask for the vehicle's VIN. Get a full Vehicle history report at Autocheck or any other place you trust ( sometimes provided by the seller ). Know how much you can afford to bid ( including additional costs ) and don't go beyond that.
Here are some more tips on how to buy repossessed cars on sale where to purchase government auction cars .
Good luck.