I've only tested with the high DC end of the spectrum so I don't have any useful data to compare. I do see mobs make their save so it's definitely not "no-fail" - that's not to say the dc is computed right - testing the lower end as you are doing would help figure that out. However, on a high DC caster I am seeing what I would expect - a high % failing saves and a small # making their saves.
I don't think you should use the first wolves next to the npc for any sort of test because those behave very differently than the other wolves, although I have no knowledge of whether they have different saves. The NPC one shots those wolves but can barely damage others.
I've heard people in game saying color spray works more than it should so the devs should definitely look into this, but I hope they fix the DC don't nerf the spell. Salt on an alchemist or sorc is much more broken than greater color spray even if the DC is broken.
On a related note, Shadowblade DC is also broken but with DC being lower than it should - there are some good test notes in other threads on that.