I think he alludes to them being unsavory things that still won't go away because there's a demand.

That's what I got out of that sentence.

I'm not quite sure why a plasma clinic would be unsavory. Maybe he's thinking of the (now illegal?) practice of paying donors?

It's more that these are ways to make money fast if you're desperate. Plasma donation is usually something people do to get paid, which is why plasma centers are usually in poor neighborhoods.

I'm fairly sure it's still legal, at least in Utah. I know people who do it on a semi-regular basis.