The claim: "If you rest due to some pain, you're weak"
Reality: Some soreness after a workout is natural, but actual pain is your body telling you that something is wrong. To workout when you're in pain makes you a fool, not tough. All you're going to do is make your injury worse, and at some point, will cause you a huge problem which will result in a long time out of the gym.
The claim: "Build muscle faster by pumping them up before your workout"
Reality: Even if you're short for time, getting a quick pump by performing high rep sets can boost the release of nitric oxide (a vasodilator), which leads to a trigger in protein synthesis. A muscle pump makes you look better instantly, but has real benefits.
The claim: "if you eat carbs at night, you're just going to get fat"
Reality: Your day to day diet is far more important than when you eat carbs. Regardless of when you consume your carbs, you need to be in a calorie deficit in order to burn fat. Some people believe in the no night time carbs theory, just like others believe in fasted cardio, but there's very little evidence proving this theory as fact.
4) Post-workout protein window
The claim: "You have 30 minutes to get your protein in or you've lost your gains!"
Reality: For the majority of us, the post-workout window is not 'all or nothing'. If you eat or have a shake before your workout, then you'll have nutrients digesting over the next few hours, so your body will have protein to feed on. The most important thing is to make sure you consume enough protein each and every day to fuel your gains. Stop panicking about your workout being a waste of time if you don't consume protein within half hour.
The claim: You must eat every few hours in order to grow!"
Reality: Don't take this one too seriously. There is evidence for both frequent meals and the standard 3 meals a day. Some people prefer to have less frequent but larger meals, whereas others prefer smaller but more frequent meals. If you're setting 'food alarms' and waking up during the night to have a shake, then you're taking things to the extreme. Waking up for shakes will wreak havoc with your cortisol and testosterone production.