I read this book in a week as part of my research to write a website on flattery. I enjoyed Stengel's supercilious comments about Dale Carnegie, author of How To Win Friends and Influence People. He's a sophisticated and stylish writer after all.
My view on business and political flattery is that it's part of the discipline of the job. Yes, it can be onerous and mechanical, but if you don't express gratitude and acknowledge people, you might be neglecting other bits of your business like providing a reliable service or answering your constituents' letters. Mrs Thatcher used to go into the kitchens and thank the staff after she had a meal. That punctilious discipline made her a great politician. There are plenty who don't bother, and they wonder why they don't get votes.
I regularly write to people in public life, usually expressing something positive. It's always interesting who replies and who doesn't.
Dale Carnegie has inspired the working practices of lots of good companies. They teach people to respect each other and be upbeat. What's the alternative? Condescension, unpleasantness, a strict class system?
There are lots of other suggestions for being good at flattery from Chesterfield, Castiglione, Benjamin Franklin. It makes for a colourful book.