Online doctor consultations are not legitimate for the following reasons:
1. You are not interacting with the doctor in person, presenting yourself for physical checking, if needed. 2. You may not know the credentials of that doctor, whether he is qualified, experienced, licenced etc.
I do not think that online consultations are legitimate. You need to check with your local doctor and get a referal to a specialist so that you can get the best treatment for you.
Basically you do not know if it's a scam or not. It's best to go around to your local doctors and do a consultation with them locally. If you are sure you want to do an online consultation then go to the Better Business Bureau and find one that is approved.
There are a lot of websites that offer free advice, which are answered by real Doctors. Check out WebMd, I use this site daily for my job, it it free and very reliable. The answers are from real medical professionals with real answers, you may have to wait for a response but it should be accurate.
We cannot rely upon the online Doctor Consultation. Doctor has to examine the patient. As you said, it is money making scams. Sometimes it may be useful to clear doubts.