Work alongside a good marketing team however, and it's night and day. I think that they have in many cases more interesting problems, especially in the context of growing a startup.
How can you tell a good marketing department? They're smart, able and willing to do math, are willing to be data and metrics driven and can't comprehend it could work any other way. If someone says to you "math has no place in marketing", you don't want to work with that marketing department.
Scientifically-minded marketing seems pretty rare. Or to put it another way: Quite often there are some scientifically-minded marketeers in the team, but no one tends to listen to them.
Good technology marketers generally are a) ex-engineers (this is a spay-shul breed of person), often those who went out in the field and sold when push came to shove or b) people that sincerely like technology and have lots of field experience.
A bad marketer says "Everything is a widget (or cpg.)" A good marketer says "Every buying process in every vertical is different and highly sensitive."
Generally, marketers arrive as communication-oriented (PR/Marcomm experience), technology-oriented (PMM/PM experience), or sales-oriented (former sales person, cares more about qualified leads than raw names and phone numbers.)
Read Steve Blank's book - most people point to him as one of the best marketers in Silicon Valley - or read about his adventures as head of the SuperMac marketing department - http://steveblank.com/category/supermac/ - That's what a GREAT marketer does.
But, yes, good tech marketers are rarer than hen's teeth. Most people in marketing are there because they lack the logical abilities to be an engineer and the courage to be a salesperson. (This is coming from a marketer.)
Generally, really good marketers know the hell out of their market, and know what metrics they're working towards. They should know every influencer in their field by name and viewpoint, if not personally. If anything, they really need to think of themselves as 'Market Response Engineers,' trying to find out what the market will do in response to the messages they communicate.
Additionally, avoid people who work/have worked at ad agencies. They know how to drink, not how to market things.