What are the signs that a root canal was performed wrong and poorly?

I mean is there like signs someone can tell that there root canal is performed wrong or poorly like pain afterwards, a long time to finish one root canal like more than three dentalk visits and still not finished, cracked messed up tooth. Cracked and messed up broken tooth worse looking than before. I odn't know cause I have a few root canals that are taking forever to be finished and I keep getting the same horrible debilitating pain in the same tooth and it was worked on more than two times already and it is still painful and not no where near being finished. I also have another tooth tha had a root canal when I was 17. I'm 29 now and I am going to a different detist than before and he took x rays and said the rootcanal went bad. I didn't even have any pain at all. The other dentist finished the root canal really nicely wirth no pain at all and you couldn't even tell there was ever a root canal done on the tooth. Now this new dentist I see cracked and drilled open this perfectly fine looking tooth that I didn't even have pain in and he sadi he had to do it he cracked it open said it went bad he has been working onit more than three times and it looks horrible and now I have more pain in the tooth than before. It is cracked all over and fractured with a big filling in the middle that is higher than the rest of my tooth. Is this a bad unnecessary root canal job done wron, poorly and abuse and neglect? I don't know. I feel like he may be taking adavantage to get more money and he figures I am just a stupi patient I don't know nothing abouyt sentistry so he figure he can get away with anything. I don't know what to do. I can't take legal action either cause I am poor and have no money. Please just anyone that can let me know if this is wrong what the dentist did and what are the signs, symptoms and appearances, if any, that a root canal is performed wrong. Also this new dentist never gives me novacaine and the other dentist I had gave me wonderful novacaine and I never feel a thing. This new dentist always tries to not use the nvacaine and he always says it shouldn't hurt but then it urts and I have to tell him I can't take it anymore please give me novacaine. And one time he got mad when said that and he rolled his eyes and was like alright I'll give you some novacaine but it shouldn't really be hurting like you say becaus ethe tooth is dead or something.