I haven't had any problem with their boards either, but that's a sample size of less than half-a-dozen, strictly AMD-based mobos. Really not definitive, and I believe the people who say they've gotten multiple bad Asus boards.
In the end, it's down to luck. Every manufacturer sends out some percentage of products that have undetected faults or are damaged in shipping. What that percentage is depends on QA and product design. I wouldn't be surprised to find that Asus had some boards with design issues that led to high failure rates, while others are solid.