"It'll sound like flattery"

There's a version of the squirm that's about character rather than nerves. You don't want to be a flatterer. You've met the people who tell everyone their haircut is wonderful, and you've watched what it does to the value of anything they say. If you start handing out compliments, you'll be one of them, and the people who matter will hear the good thought as noise.

I'd separate two things that this belief runs together. Flattery is a compliment with a motive attached. It's said to get something, a favour, a good mood, a place in someone's regard, and it's said whether or not it's true. A good thought said out loud has no motive. You thought your dad was patient with the children. You aren't after anything. You're reporting what you saw. That's the difference, and it's a difference in the speaker, not in the words. The same sentence is flattery from one person and a report from another.

There's an odd piece of evidence that bears on the fear, though it comes at it sideways. Roos Vonk, a Dutch psychologist, ran experiments in 2002 on what she called ingratiation, which is flattery in the researchers' vocabulary. She found that people who were flattered gave the flatterer more credit and liked them more than onlookers watching the same flattery did, and that this held whatever the target's mood, motive or spare attention. Even flattery, in other words, lands better with its target than the people watching would predict. I'd hold that lightly, and I'm not suggesting you flatter anyone. But if a compliment with a motive doesn't get thrown back, a compliment without one is not the risk you're treating it as.

The person you're afraid of becoming didn't get there by saying true things. They got there by saying untrue ones, and saying them to everyone. You're in no danger of either. Your drawer is full of specific, accurate, unrepeated observations about particular people, and the only thing that stops a specific true observation from being flattery is that it's specific and true. "Your haircut is wonderful" to everyone is flattery. "You asked the two questions I wouldn't have thought of" to one person about one call is a fact.

If you want a rule, here's mine. Never say it to get something, and never say it if you don't think it. Keep those two and you can say as many good thoughts out loud as you have, and none of them will be flattery, because none of them will be doing flattery's job.