The issues with bringing a dog to work (and more generally, with raising a dog) are similar to personal hygiene. Some people raise a dog properly — you then get well-behaved animals that are a joy to be with. And some people just don't care too much.
Just as you can't generalize about programmer's hygiene (or can you?), you can't generalize about how dogs behave at work.
And BTW, raising a dog is a commitment many people should not undertake. It requires a lot of work and dedication. All too often people blame problems on dogs, while it is practically always the human who failed.
Raising (and properly training) a dog is wonderful opportunity for the trainer. You'll practice patience, creativity, empathy, and the value of having a long-term plan. These are maybe not bad skills to develop as a hacker or startup founder.
That said, some of the most trainable dogs are the easiest to get into trouble with and I speak from experience. Most people probably don't have enough experience to gauge the effort or different ways to undertake a dog training program.
I recommend Karen Pryor's "Don't Shoot the Dog" for people interested in training philosophy. Be aware, there are rabid (sorry, couldn't resist) advocates for various dog training approaches online and they take great pleasure in destroying forums, online discussions, and generally making sure that only their viewpoint is "the one true way."
However you can generalize about their production of dander that's allergenic to some people (see my other comment in this submission). Unfortunately nowadays I can only enjoy the company of dogs when outside :-(.
Just as you can't generalize about programmer's hygiene (or can you?), you can't generalize about how dogs behave at work.
And BTW, raising a dog is a commitment many people should not undertake. It requires a lot of work and dedication. All too often people blame problems on dogs, while it is practically always the human who failed.