Using arousals is not a big deal. It only becomes an issue depending on the intentions for which it is been used.
Some individuals or group of individuals use fetishes because their natural arousals are slow, so their partners can help them get to that place.
Notwithstanding, there is always a down side and an upside to every coin if there is. Before engaging into fetishes, be clear how far to go. Have your code words to call for a fault if any of both parties can't take it any more.
Don't ever over exhaust your human resources. There may not be any line, but, how far you can resist you should be able to call your partner.
My candid advice is for you to stay as natural as possible. Most fetish practices end mostly in trauma and self doubt - the worst is heartbreak. So as you engage, know the road you are taking...