A good way to tell if a roofer or tradesman is any good, based on their website, is if they post educational content. A good tradesman takes education seriously because he’s probably seen the detrimental effects of being undereducated.
For example, they may take the time to write an article on how to do something or why it is done. You can get a sense of their knowledge on the subject.
Another way to tell if they are skilled, is if they post articles about opposing techniques. For example, they may explain why they do something a certain way while other roofers do something another way.
One thing to watch out for is when they just copy and paste stuff - regurgitation of crap. You can usually tell through bad grammar and composition.
And as I mentioned before in other post, the roof consist of several key steps and systems that makes it water proof. Miss just one step, its no longer water proof. So its important for you to do your due diligence and take your time when finding a roofer. Because it has to be done right from the start.
Granted, many roofers don’t have a good website and are more traditional but may still be skilled. That is when you personally as the consumer, need to know about the roof itself. There’ a good source to learn about this - books. Homedepot sells books on home repair that are excellent to get a feel for the roof components and what needs to be done in order to have a proper water runoff.