When I played in tournaments, at the start of a game, my opponent would ask my rating. I knew he was forming an opinion about my playing strength based on my rating. But performance and strength are two different things. If rating determined the outcome of the game then no player rated higher than his opponent would ever lose.
At the chess club I here comments by wood pushers that told me they sized up a player's strength by their rating. This is a faulty way to approach such an assessment. A chess players playing ability can be dramatically reduced by the stress he/she may be enduring at that time. A divorce, job change or a move are considered the highest three sources of stress. I am a chronic pain patient and I know my performance ability is dramatically affected by pain.
Another good example is former World Champion Mikhail Tal (RUS). He was a brilliant player and he had could beat anyone in the world. But he suffered kidney problems for many years that eventually caused his death. Obviously this illness caused his tournament performance to suffer as his health wavered. When Tal's FIDE rating dropped below the top 10 in the world, did that mean he was not a dangerous player anymore?
On days when he felt good, his chess genius was capable of destroying any opponent. A few years before his death, he won the World Blitz Championship! In that tournament Gary Kasparov was eliminated.
Next time you are paired in a tournament, your opponent may not be at his best. Play each round and ignore your opponents ratings.
Especially if your opponent is a stranger and you don't know their history. Remember ratings are a reflection of past performance.