Had an interesting experience with this flying SEA-TUS this morning.
The row across from me where my travel companion was sitting had 4 service dogs sitting there that belonged to a mother and her daughter, all of which were out of their carriers for the entirety of the flight. In addition to that, a couple sat down in my row with one of their dogs, and shortly after one of the 4 dogs across the aisle started growling at it, causing their dog to shake uncontrollably and resulting in a pretty tense boarding process.
The couple's dog in my row did not appear to be a service dog as it was required to go into its carrier after boarding, and I noticed they were quite irritated that the rules seemingly did not apply to the dogs across from them.
Also, at some point throughout the flight, the owners of the 4 service dogs were asleep, and my travel companion had to physically prevent one of the dogs from entering the aisle and escaping their row.
Sure was an interesting flight nonetheless, and it seems like there's a lot of people abusing this policy. I can't imagine why anyone would need 4 dogs with them at all the times on an airplane, unless they're simply trying to take advantage of the overly lean regulations.