It does get really hairy. Having read a few technical related warrants (and by no means can I speak to many), they are truly using every last bit of persuasion to convince a judge to sign the warrant and usually request to sweep as much information as possible. They start off with all their goofy worthless technical qualifications eg "3 week cyber security training at McAfee Sleuthing Summit". Then proceed to go into the facts of what they discovered, blending it with the story they believe is true (and in the case I know of wasn't true and was a narrative that was an extreme over exaggeration). The judge signs the warrant then later on if you were actually charged, you have the legal knowhow, and/or massive amounts of money, you could challenge the sweeping nature of the warrant or grounds it was signed upon.
In this case it didn't really matter much though... they were able to cause great annoyance to a third party and the law enforcement folks involved will likely never be held responsible.
I think its really important for the judge only to look at the facts and to decide to sign based only upon that. In this case, the facts were probably very weak. I'm not sure what other contents could be possible other than, "this was the last known IP address for this packet containing child porn, can we search their premises and copy all their data plz"