I'm not sure it's been confirmed that she is actually ON dialysis currently. I think some people had indicated that she had received a kidney transplant years ago, and recently had been consulting with her transplant team. Obviously kidney failure is a serious issue. But we don't know the full extent of her medical issues, nor should we. She's revealed enough information to enough people to piece together a rough sketch of what she's going through.
If I remember correctly, the person who questioned whether the kidney story was true actually received their reading on time. They had inquired about their reading on the 4th business day when Lady P's site says to expect a 3-5 business day delivery.
With that being said, I'm not sure WHY it would be unethical for her to provide readings because she has kidney disease. If she's NOT on dialysis and is more than a year removed from her transplant, she not eligible for disability (in the USA) anymore unless she has other medical issues that prevent her from working. Also, some people on dialysis work full-time jobs even though they are eligible for disability. It depends on the person and how they tolerate dialysis.
If she has been dealing with the issue for an extended period of time, I'm sure she's been able to ascertain her physical and emotional limits in relation to her illness and its effect her psychic ability. Plenty of readers deliver subpar readings without the excuse of a a chronic illness.
I had one email reading with her at the beginning of the year, and her predictions seem a little farfetched to me. I haven't had a lot of luck with readers, unfortunately. BUT, having read with many, I don't think Lady Persephone is unethical or a scammer.