Google AdSense and Yahoo! Publisher, Linkshare and Commission Junction, Chitika eMiniMalls and Kontera in-text ads… With so many options available to bloggers, it’s tempting to plaster your web pages with ads. But is more really better? And how much advertising is too much?

When it comes to web advertising, there is no single formula for success (you’ll only find out what works for your site by conducting ongoing testing), but I’ve found that less is often more.

Why?

1. Too much advertising can get you blacklisted.

Okay, you’re not likely to be dumb enough to make this mistake, but advertisers do set guidelines on how much advertising you can place on a page. Google AdSense, for example, limits you to three ad units on one web page. Be sure to read the policies for your advertising or affiliate programs.

The last time I ran a test on one of my blogs, my CTR went UP when I went from three ad units down to one.

2. Too much advertising can overwhelm your content.

If your blog looks like a splog (a blog that’s full of spam), it may send your visitors rushing for the exit. How long would you watch an hour-long TV show if there were 55 minutes of ads and five minutes of content? And how credible is a program if it has INFOMERCIAL written all over it? If your content isn’t valuable and weighty enough to stand up to the advertising around it, your readers will hit the back button and look for the next Google Search result.

3. Too many ads can be just plain annoying.

I feel this way about in-text ads, those fake hyperlinks that highlight keywords but reveal popup ads instead of editorial links when you hover over them. I tried Kontera in-text ads, and they showed some promise, but I found them so irritating as a reader that I decided not to subject my visitors to them.

When you test your ads, make sure you monitor your page views per visitor. If you notice this number going down, it may be because your ads are sending your visitors running as soon as they hit your site.

4. A confused mind can’t say “yes.”

If you give people too many choices, they’ll want to think about them—and the more they think about them, the more likely they are to be struck with paralysis by analysis.

Consider Tech Reality #1 from the Men’s Health 2007 Tech Guide: The more products you consider, the less likely you are to purchase anything.

In a recent study, psychologist Sheena Iyengar, Ph.D., and her colleagues at Columbia University set up a display table at a gourmet-food shop and offered samples of an expensive imported fruit spread to passersby. Those who stopped were given a coupon for $1 off any jar they bought. One day, six flavors were displayed; the next day, 30. More people stop ped at the 30-jam display—and more taste-tested those jams. However, they were one-tenth as likely to buy as those who stopped at the six-jam display for a sample.

Lesson: Having lots of information may increase your page views, but if you’re selling a particular category of product, you may make more sales by featuring one or two choices, rather than joining every affiliate program you can.

On the other hand, Men’s Health also selected the Microsoft Zune as their number one pick, so…

5. The right amount of advertising is a moving target.

How much advertising you should have on your blog depends on a number of different factors, and it’s a moving target. The right answer depends on your content, your readership, your design, seasonal considerations, and any number of other factors, including the ads themselves. Change any one of these factors—your design, or the number of subscribers versus Google hits, etc.—and the right formula can change.

Testing will help you fine tune your site, and constant monitoring and tweaking will enable you to mine the most revenue from your readership. But beware of “ad creep.” If you notice your pages look ad heavy, or your CTR is going down, try cutting back. Sometimes, less really is more.