I also have had some trouble deciphering what sickness my hair is suffering from..lol. Build up is the most obvious one for me. My hair starts to get more tangled, less shine, and sometimes it will feel weighed down and heavy, and may even look darker. I found the biggest culprits for me are hard water and silicone laden products. I have stopped using most silicones, and my hair loves it! It is much curlier, but it took a couple of weeks of dealing with fuzziness while my hair adjusted. I use a clarifying shampoo once a month (Neutrogena) to get rid of buildup. I usually like to try natural remedies/treatments, and using a AVC rinse or lemon juice rinse have been recommended on here, but I don't like the thought of putting vinegar in my hair, and since my hair is color-treated I'm afraid the lemon juice would strip the color.
When my hair woes are from dryness (more in winter) my curls are more undefined and surrounded by frizz, the strands feel more wirey, and my hair looks puffy overall. I only use a sulfate shampoo about 2-3x a month (and condition wash about once a week), which really seems to help with frizziness compared to washing more than this. Using a honey rinse after shampooing adds a lot of shine too. In the winter I use a lightweight leave in co, and put in a deep treatment about once or twice a month.
(Both of these routines would not be affective if I still used silicone products, however).
I really have never felt what over-conditioned hair feels like, but I'm imagining it would leave your hair feeling soft, but flat, curls would have less definition, and the individual hair strands would be weaker and more prone to breakage. Some people with fine hair get this result when they use products heavy in oils. My hair seems very porous and soaks everything up (I have medium textured hair).
Heatherbee-You really do have pretty curls! I like to use crunchy/max. hold gels, and sometimes scrutching my hair a lot when mostly dry takes away the producty look for me. Do you like the Fx gel? I always look at it when shopping (I love how it smells) but have never heard anyone talk about it.
Co-wash: Hair One Argan Oil or Burt's Bees GreenTea and Fennel
Low-Po: Devacurl LP or SheaMoisture Black Soap(1-2x/wk)
Condish: SheaMoisture Deep Repair Mask
Leave-in: Kinky Curly Knot Today AND
Styler: GF Curl Construct Mousse or Biotera gel
Treatments: Oils or butters,and trying out Aubrey Organics GPB for protein