By the time someone says "let's take this offline," you've usually already lost the room. Reading it well means noticing the signals well before that sentence gets said.
Reading the room comes down to a small set of specific signals, not some vague instinct you're either born with or not. Eyes moving to laptops or phones. Questions that repeat something you already covered, meaning people stopped following a few sentences ago. A shift from active nodding to passive stillness. Any one of these on its own means little. Two or more at once is the room telling you something, whether or not anyone says it out loud.
Noticing the signal isn't the mistake, pushing through it is. Most people catch these cues just fine, then keep going anyway, usually out of a fear that stopping mid-point looks like losing confidence. That's backwards. Adjusting in response to the room is what confidence actually looks like. Talking at a room that's already checked out is what looks unaware.
You notice three people glance at their laptops the moment you start walking through the third data table. Instead of finishing all four tables as planned: "I can see this is a lot of detail, let me jump to the headline and we can dig into the rest if it's useful." That single sentence, said at the right moment, does more for how the room sees you than finishing the original plan ever would.
Reading the room also means matching its energy. Walking into a tense post-mortem with the same upbeat energy you'd bring to a kickoff reads as tone-deaf, even if your content is exactly right. Walking into a celebratory moment with flat, businesslike energy reads as if you don't actually care about the win.
Silence is its own signal, and it isn't always agreement. It can mean agreement, confusion, or disagreement people aren't comfortable voicing, and treating all three the same way is a common mistake. If you sense it's the third one, naming it directly usually works better than moving on: "I'm getting quiet, is there a concern nobody's said yet?" That question alone often surfaces the actual issue the room was sitting on.