You will definitely get clients in that are solely there because they want a cheapy massage and then they move on to the next good deal but it is possible to make a lasting impression on clients just looking for a good therapist.  I ran a special on Eversave-I think they do a little more to make people repeat clients by offering them a $5 rebooking coupon they can use towards their next Eversave purchase-and the first person to come in was  a personal trainer who is now referring her clients to me.  I made up some referral coupons for her just special to give to her clients.  That alone made the deal worth it to me.

Groupon is great for goods, as it's easy to sell many. Just order more and sell more.

With services it's a whole another question. It's very hard to give a quality experience and still make a living with those huge discounts. Also, let's say you do a Groupon massage for $30. You usually receive 50% of that price. So you make $15.

I've seen pretty low numbers of repeats, one MT mentioned 3% repeat clients after a Groupon. So yes, Groupon clients are price hunters. Price hunters usually do not look for relationships.

If you still want to do a Groupon and are aware of those shortcomings, then it might work for you. The most important thing is to favor your existing clients. Never turn down an existing client for Groupon clients! The way to do this is to set a day or two per week for Groupon clients. That way, you don't get burned out. Hope this helps!