NEW YORK (CNN/Money) – To every miffed reader who has written in complaining about the recommendations in CNN/Money's Holiday Tipping Guide, let me just say I couldn't agree with you more.

That's right. No matter how many times I write about the issue, I fail to see the rationale to the tradition as it exists.

Some people get tipped. Others don't. And it has nothing to do with whether they earn a living wage, either. Of those who do get tipped, some people get tipped far more than others, and not necessarily because they do more or harder work.

To make matters worse, there's no consensus among tipping experts as to how much is appropriate to give.

"There's no law and no rules and regulations," said Stacie Krajchir, coauthor of the "The Itty Bitty Tipping Guide."

And yet, every year people always want to know "What should I tip?" Everyone wants a list.

"We crave structure," Krajchir said. But, she noted, we resent it, too. That's made quite clear from the countless reader emails I've received.

They fall into several categories:

Oh, yeah? Tip this. "I should not tip anyone that is lucky enough to mow my lawn. There are 50 other guys bidding for the job."

What? Are you on crack? "Whoever made up your tipping guide did it before they woke up in the morning or while smoking marijuana doubles."

Hey, what about (fill-in-the-blank)? Among the jobs readers said should have been included in the table were: School bus drivers, church organists, parish priests, limousine drivers, mechanics, full-service gas station attendants, pizza deliverers, children's private music or ballet teachers, and those who work in office and support agencies.

Personally, I wouldn't include all of these categories on my tipping list. But tip away if someone performs an important service in your life that you want to recognize.

Why should dog groomers get less than hairdressers? "There's no comparison ... in the amount of work involved. Groomers must handle dogs and cats of all temperaments. We must do nails, ears and anal glands. Bites and scratches come with the territory. Many of us get rabies shots to protect us from ... dogs whose owners may not care enough to vaccinate. (Plus), many cats and dogs bounce, squirm, shake and wrestle through the entire process and those are the cooperative ones."

I had no idea. I'm guessing neither do the dog owners who regularly drop their pooches off on their way to the salon, where they're all too aware what their hairdresser does. That may be one reason tips for hairdressers tend to be higher.

It also may be that "the older tipping situations (hairdressing) have more of a set tip," Krajchir said. With more personal services gaining popularity, it's less established how much is appropriate to tip.

What's the deal tipping the FedEx guy more than the UPS guy? "Do you hate UPS drivers?" No, I think they're swell.

I used the recommended amounts from Hilka Klinkenberg, founder of Etiquette International, who suggested $15 for the UPS driver and no cash but a gift under $25 for the FedEx courier. In prior years, she said, that's the guidance she received from the companies.

Maybe something changed. When I called, a FedEx spokesman said FedEx couriers are not allowed to accept tips. A UPS spokewoman said the company doesn't encourage tipping. But, she indicated, it's not as if drivers get in trouble if they receive them.

So you decide.

Disgruntled postman here. You've ruined my Christmas. Well, that certainly wasn't my intention. Civil servants are not allowed to receive cash tips, and the U.S. Postal Service asks that your gratuity not exceed $20 in cash value. But there's no question that many people disregard the no-cash policy.

If I were to tip everyone on the list I'd be broke. Yup, most of us would. That's why I never said you should tip everyone on the list.

The only people you should even consider tipping are those folks who provide services that are important to you, and which you use frequently throughout the year. This assumes, of course, that you're happy with their work.

If you do decide to tip, how much you give depends in part on where you live. Tips in New York and L.A. are likely to be higher than in a rural or suburban areas in, say, Wisconsin.

If cash is spare, but you want to acknowledge someone's services, give a small gift instead, such as homemade baked goods. The thought is as important as the tip itself.