A deck railing needs to withstand a 200 lb force exerted laterally against it. The perfect installation of a wood deck will have 4x4 or larger guard posts bolted and blocked to the joists. This makes them extremely sturdy. You don't have to worry about 2 adults leaning against the railing and having it give way.
Then there's this deck installation in Omaha, NE that I ran across this week on my home inspection:
At first glance, the railing looks beautiful and sturdy. Then when I grabbed on it, I could easily move the entire railing a good 6" on both directions! They took 2x4's, routered a groove down through to make them appear like 2x2's, and screwed them together to make a box with a hollow cavity inside. They then toe-nailed them into the deck boards instead of bolting them to the joists below. The entire handrail was done this way also. If I wanted to, I believe I could have pushed hard enough and tore off the entire railing. How insane!!! ...but it looked good;-)
For more crazy issues we run across, check out our photo galleries on our website: