Honestly I only think it's dangerous if you're doing it silly and people know you bot, keep a low profile. Unless blizz is getting reports of you banning all the time I don't think you'll draw attention to yourself.
A few things I do on farming accounts :
-Get into a guild ( the one i'm in just randomly invited me , for all they know I could speak a totally different language, plus none of them really speak in guild chat anyway)
-Change your farming spots every so often, go at different times
**** Use the premade group finder and find a different server **** This is key imo, if you farm on a different server every other day people won't recognize you as much. Also if there is a legit farmer there and they see, they will probably get upset and send in a ticket ( pretty sure that's how my last bann happened )
-When posting in the AH always do in on a different character then your farm character , I even make a couple characters that sell if legit farmers see the same name posting mats everyday they will get suspicious and try to find out who you are.
Other then that the rest of self-explanatory , do what you thinks right.