Whilst they can detect you if you're in front of them if they're making the clicking sounds... They're so ineffective at seeing, i'm confused as to why they're considered such a thread in the games world. A blind enemy just isnt all that dangerous.
The game seems to contradict itself with the Clickers. When you first meet them it says they use echolocation and you must hide behind something while they are clicking about or they will see you and rip your throat out. Later on the game says that as long as they are clicking around and you aren't making noise then they won't "see" you. Personally, it doesn't make a difference to me since they are still a huge pain in my **bleep**. If they weren't so fast or they didn't one shot you then I wouldn't mind as much but they are ridiculous as is.
Its a game..... suspend some disbelief or you'll ruin the game for yourselves.
Cognitive Dissonance - The ability to understand multiple viewpoints even if they conflict with one another - and still use critical thinking, logical thought, and common sense to come to the realization that only ONE is the correct one and the others are wrong.