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.

Favourites:
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...