I have a Soligar 28-80 C/D macro that's probably the most craptastic lens in my arsenal. I suspect its less the lens itself being bad due to design but from abuse in its life before it landed in my care. I bought an old ME kit for $12 due to it having a Pentax-M 50 1.4 in it, and it wound up tagging along for the ride.
Granted, the lens also has a six foot minimum focus distance, even at 28mm, which made my brain lock up a bit as I tried to comprehend the whys of that setup.
The lens actually *crunches* as I try focusing it in and out.
That said, it does produce some wild bokeh...