I shampoo whenever my hair feels like it needs it - it's hard to describe, though. It's sort of like it feels a little less clean than it would normally - not really oily just... gunky. It doesn't look very different, but it does feel slightly different. I can normally tell when I'm wetting it in the shower - hair that doesn't need cleaned for me feels quite good (like seaweed, as they say), whereas hair that needs cleaned feels really tangled, and sort of... coated. Ish. As I say - hard to explain. I end up using a lo-poo around once a week or so on average - depends on what I've been putting in my hair. I seem to be able to overcondition reasonably easy, so I also shampoo if that happens, just to try to reset the moisture balance.

I will also lo-poo if I've been sweating a lot or exposed to all sorts of environmental dirt/wind/etc. This past weekend I did a lot of hiking, so I ended up just lo-pooing every day.

As far as popular lo-poos go, I'm not sure what all is available in the states... but I currently use Burt's Bees Super Shiny shampoo (available all over the place), and have really good results with that.
3b/c. Fine, med-high porosity, normal elasticity. Hair loves oils in summer, protein in winter. Constantly battling the hard water monster.

CJ Curl Theory, Curl Rehab, Smoothing, Curl Fix, Daily Fix, CCCC, CIAB, CQ, SSCC, MC shampoo, Inecto Pure Coconut Oil, CP luscious curl creme (summer), DB Pumpkin Seed (summer), FD/MT, JCWDT, JCTS

American literature PhD student in the UK...