Generic monster is really hard to do. I've heard too many people complain my YCH is not detailed enough to want to bid. I don't want to do a detailed sketch and have to re-do it just to make it fit the generic. u_u That defeats the purpose unless people are willing to pay for me to redo the sketch.
Huh, I've never heard of complaints like that... Maybe only humanoid monsters then, think like a werewolf shape. I just know a lot of people have anthro monster/creature characters, and it might help with generating more interest in your commissions to have some examples C:
I enjoy your cheaper mixed sheets, but I don't think that was helpful to what you was asking but it is nice to give a mix and offer variety. maybe mix up the guaranteed popular ones (canine, Human, Dragon, etc) with one or two more niche ones (Bears, serpents, rabbits, etc)