Yea these were done over a while. I agree with your sentiments as well. Hopefully I will improve enough to made the other monsters higher wuality as well.
Great set, I think the second and last monster in the first column are far superior to the others in technique and pose. A lot of the other monsters have a blobby shading style. Any chance you did them later than the others? I assume this was done over a long period of time as I also recognize the slime from a while back, and I'm sure you've improved significantly while drawing these. =]
Anyhow, good work.
I knew I recognized that slime!