For many native English speakers, the phrase "work the room" will have negative connotations. Often that phrase is associated with people who tend to use their relationships with others primarily as a way to benefit themselves alone. Any benefit to the others in the relationship is strictly secondary, often unnecessary, and sometimes even just a tool for the person to further exploit the relationship to their benefit.

I don't think it is a coincidence that the phrase is very often applied to politicians. In fact, I would venture to guess that politicians are the group this phrase is applied to the most often.

I'm not saying that everyone who "works the room" is a politician, and I'm not saying that all politicians are strictly self-serving individuals (yes, there are some good ones out there). However, there are enough examples of politicians to whom the phrase is applied, that it is often associated with them. There are also enough self-serving individuals to whom the phrase is applied that it helps to give the phrase a negative connotation.

And, obviously, there are quite a lot of individuals who have both the "self-serving" and "politician" categories covered.