From what I have learned in the last 7 months of being a member, a good creative hub should be about 1200-1800 words in length, depending on topic. I have several hubs that draw significant traffic, which are longer than that.....more like 2000-2500 words. There really isn't a guideline, but what I have learned as stated is from most of the veteran hub writers here.
Again, it is quality and originality of content is what works. Read more hubs, like that of Relache, Nelle Hoxie, Sunforged, Ryankett, Darkside and Thisisoli. Each are veteran hub writers here.
I hoped I helped. :)