Like others have said, good manners cost nothing, and bad manners are a personal bug bear of mine.
I hate it when people don't say please or thank you. When people don't either write a thank you letter, or at least phone after receiving a gift, also shows the height of bad manners.
Strangely I've found it to be the socially climbing middle classes who appear to be the most ill mannered. Those at the top and bottom of the so called social scale, share amongst other things respect, and good manners. It is those odious people, who think they are proving themselves better than others by being rude, that have the real problem.
If the sad people who think clicking your fingers illicits better service, they are mistaken. They are more than likely to ingest the waiter's saliva with their soup, or indeed have had their soup spoon put somewhere where spoons really shouldn't go.
