Relentlessness is a big turn-off, she says, adding that salespeople will often "say anything to get what they want."

Urizzola says his company's big ERP deal almost fell apart after IBM got involved, insisting that Saladino's had to buy its hardware from a particular reseller. "I had to call the senior VP at SAP to tell them to tell IBM to back off," he recalls. "They just wouldn't let it go."

Mr. Know-It-All

The salesperson who thinks he has all the answers is particularly annoying. His knowledge is doubtful, but he's never at a loss for words. He won't admit that he can't answer your question, so he often responds like a slippery politician, talking around the question endlessly without providing any real detail.

"I'm a very technical person, so I listen to detail, but a lot of these guys speak in boilerplate," says Koppel. "I appreciate it when someone says, 'I don't know, but I'll find out and get back to you.' It makes you feel better about the answer when you get it."

Cousin Clueless

The flip side of Mr. Know-It-All is the salesperson who clearly hasn't done his homework, knows nothing about your business and comes to meetings unprepared.

"I've dealt with reps that don't know what they're doing, and it's clear they're dealing from a script," says Goodbaudy.

"Hardware resellers don't seem to do any homework and don't seem to care what we do," adds Urizzola. He surmises that this may be because hardware is a more interchangeable commodity than enterprise software, but the impersonal and unresearched approach doesn't help grease the wheels of commerce.

The Entourage

This is the sales rep plus posse. He shows up at meetings with a large team of co-workers (usually including his boss) with the intention of upselling you. Larry Pritchard, CIO at Schaeffler Group North America, refers to this as "non-value-added overhead."

According to the pros we interviewed, this tactic rarely succeeds. "We've already talked to the rep about what we want, and my team has already defined our requirements, so now we've got to shut it down," says Pritchard, explaining how he handles upsell come-ons.

Koppel recalls an instance of having a modest $10,000 item to purchase when the vendor showed up with nine business associates in suits. "I'm sitting there wondering how much of what I'm giving them is to support the nine guys in suits," he says.

"They think that once they get their foot in the door and sell you one thing that they can then sell you five things," Goodbaudy adds.

Fighting Back

Technology may change, but human nature is constant. In dealing with all these archetypes, our IT pros say there's no substitute for due diligence -- and experience. "Salespeople have remained pretty much the same over the years," says Koppel. "But every time I see a new trick, I file it away."

The key for IT buyers is to be prepared, know exactly what you need now, recognize what you will need in the short and medium terms, and understand how the new systems will interact with your existing systems. It also helps to have your baloney meter on high alert and to know how to say no.

Ultimately, if you're not getting any satisfaction from your tech provider, the solution is often straightforward: Vote with your feet and take your business elsewhere.