In today’s online world, marketers can’t afford to do advertising the old fashioned way. They need to rely on automated programs that serve ads to the right audiences in cyberspace.

One question I hear often from business leaders is to what degree of confidence should they place in these automated programs to actually deliver what is promised. There’s a nagging concern that some of the promises might be a bit more like “blue smoke and mirrors.”

As it turns out, some of that concern may be well-placed. Here’s one recent example of problems along these lines. And Trust Metrics, an online media rating firm, has studied more than 500,000 unique web domains – in effect, “taking inventory of the ad inventory.” And what it’s found is pretty sobering.

For starters, the online ad inventory supply is marked by dynamic change and constant evolution. Approximately 20% of the domains studied by Trust Metrics in late 2010 don’t even exist anymore as of the end of 2011. Tens of thousands of sites that may have once been vetted by agencies or networks are gone. There is no content at these domains … or they’re simply “ad farms.”

Trust Metrics claims that never have so many marketers purchased so much online ad inventory in an environment that is so degraded, a significant portion of the domains might not even be around a few months from now.

Moreover, approximately 10% of the domains Trust Metric evaluated that sell ad impressions in scaled buying environments (e.g., exchanges and networks) are actually non-English language sites – hardly valuable places to advertise. Plus, that represents more domain names than those identified as pornographic, or containing significant profanity or hate speech.

Trust Metrics’ evaluation also found that well over half of the sites available in large ad networks are what it classifies as “substandard environments which don’t adhere to even the barest minimum in publishing or editorial principles.

The bottom line on this is that of for 1 million domains that sell ads … most advertisers wouldn’t want to be on ~600,00 of them!

Of course, the flip side of this is that there are thousands of sites that do perform for advertisers – and those “good” sites drive valuable clickthroughs, sales and brand building.

But clearly, advertisers would be well advised to adopt a “buyer beware” stance in the current online advertising environment.