Nick K.

I made the mistake of not seeing the reviews prior to using Viagogo. Sold four tickets worth a total of $2000 on their website.

They claimed the tickets weren't valid, and not only refused to pay me, but also charged my credit card an additional $650.

Would not recommend ever using this site.

Groupon has presented me with some great deals over the years. Some of these deals have been wasted money (due to the fine print, not being able to schedule a good time with the vendor), while others have been very worthwhile.
I would caution anyone from adding their credit card to Groupon. There isn't a checkout page so as soon as you click the 'Buy" tickets/Groupon it'll charge your credit card. Groupon will then refuse to refund your order, even if you didn't intend to purchase the item or ticket. Be aware of this.

-Nick