I've used the normal NC stuff as well. I regularly deep-condition with olive oil/rosemary oil. I have done a DT of olive oil and avocado. It really works, but I don't have a food processor or blender, so two days later I've found fine pieces of avocado in my hair.
The worst things I've used have been coconut oil and and shea butter by itself out of the jar. The coconut oil took forever to get out and was really greasy. It also left a white film on my hair. I've never used it since. I get great results with coconut milk, though I only leave it on for 20 mins to an hour. When I left it overnight, my scalp itched.
When I was younger I went though a mineral oil phase. That was horrible on my hair. I also used some coconut oil concoction that was for both body and hair. Needless to say, both left my hair unnaturally shiny (greasy). I was so afraid to touch my hair or lean my head on anything, because I did not want to leave a stain.