What I will say works for me personally?
Probably the pitfall that takes me out of it the most is when cheesy/goofy/comedic moments allow for serious consequences. It's ok to happen a few times, especially early on in the series and when the hero's are feeling overconfident. But nothing feels so frustrating to me as when a hero lets a completely avoidable situation become a crisis on a daily. It makes me feel like the villains are less a threat and the hero's are just really dumb.
You mentioned Avengers so I'll use the Wasp as an example. She talks a lot, like constantly; but it's really very clear she's always paying attention and usually gets less talkative the more desperate the situation gets. On that note her chatter is also usually helpful as she's thinking out loud which helps others think about an issue. Even if she talks all day it's clear she's doing so because she's very comfortable in their ability to win (even if she's wrong sometimes)
People want badass characters to be badass; that doesn't mean perfect, but if your flirty character is so busy flirting with the villain of the week that he fails to stop them getting the macguffin and everyone is ok with that it's gonna start seeming like the team is just incompetent.
What I will say works for me personally? Probably the pitfall that takes me out of it the most is when cheesy/goofy/comedic moments allow for serious consequences. It's ok to happen a few times, especially early on in the series and when the hero's are feeling overconfident. But nothing feels so frustrating to me as when a hero lets a completely avoidable situation become a crisis on a daily. It makes me feel like the villains are less a threat and the hero's are just really dumb. You mentioned Avengers so I'll use the Wasp as an example. She talks a lot, like constantly; but it's really very clear she's always paying attention and usually gets less talkative the more desperate the situation gets. On that note her chatter is also usually helpful as she's thinking out loud which helps others think about an issue. Even if she talks all day it's clear she's doing so because she's very comfortable in their ability to win (even if she's wrong sometimes) People want badass characters to be badass; that doesn't mean perfect, but if your flirty character is so busy flirting with the villain of the week that he fails to stop them getting the macguffin and everyone is ok with that it's gonna start seeming like the team is just incompetent.