Oh dear that sounds dreadful! Well I'll give it a go and see how I get on. When you say it's very soft and marks easily, I presume this is when it it's being applied. Does it harden adequately with time?
I'll be decorating the side of this dummy with a running garland of flowers made from petal paste. I'll be fixing them individually with royal icing. I hope this Covapaste is up to the job and doesn't start sliding off under the weight of the flowers! I think you're right about the odd bad batch. Tesco own brand seems to fluctuate between hard and soft that's why I preferred Dr Oetker. Perhaps this should be another thread!
Thanks again for your thoughts.