First, I didn't look at the pictures so had a hard time finding the place. I was looking for a building, but it is just an unassuming grey shed/box just in front of the car wash facing Pecos in the Sinclaire gas station at the corner of Pecos and Russell. I saw the Go Green Smog banner on it but thought it was advertising for a building near by. I even drove between it and the car wash without realizing that was the place. Duh. Don't make my mistake... look at the pictures.
Once you find the Go Green shed, just park next to it on the immediate right; to right of that would be the gas station's air/water pumps. Alex, the owner, will come out from behind the plastic curtains when he sees your car. Alex is a young guy, very friendly and interested in offering great customer service. He worked for 2 years at a smog/service station and started this current business a year ago to focus solely on smog testing.
I mentioned that I found him on Yelp and he offered to give me the $2 off coupon, taking the price from $19 to $17. He mentioned that if the smog test fails, he will do re-tests for free. Because he doesn't offer repair services and does free re-tests, I know that he has incentive to have the smog test succeed.
The test only took about 5 minutes. First, he scanned the VIN off the front door's label and visually confirmed it. Then he attached some wires to the engine compartment (I didn't make the effort to find out exactly where) and the tests ran for a couple of minutes and was done. He gave me a smog test pass receipt and I gave him the payment. (The results are also immediately transmitted electronically to the DMV.)
I didn't use the coupon and paid full price because I wanted him to still be in business next year when I will need to do another smog test. Great price. Friendly service. You can't go wrong with Go-Green Smog.
Update: Came back a year later and still found the service excellent. Alex's brother (I think) was working this time around; he is also very friendly.