I bought some yesterday from TK Maxx (a brand called Ellie, I think). They looked great before they were put on. Once on, my legs appear to have gained approximately a stone each. My knees actually look fat and pudgy. This is not on. The knit is also stretched so wide that you can see shiny lines where the lycra is catching the light. I bought medium/large which according to the packet is perfect for my size/weight, so that's not the issue.
I have never had this effect with regular black opaques (even the knit/merino version).
Can anyone recommend any others? They have to be completely opaque. I have checked M&S and the only grey version online is a mere 40 denier. I'm looking for 100.