Warning: restaurant.com refuses to remove restaurants from its website which customers report are no longer accepting gift certificates (coupons).  They have no problem selling GCs to such restaurants however.

An example is:

• Kabul Kabob
• 6802 Commerce St
• Springfield, VA 22150
• (703) 451-3373

I reported months ago that they would not accept it anymore but  restaurant.com has not removed it.  I even called back and asked why and they said restaurant has not told them to no longer accept but they have no issue with giving credit for restaurants not accepting them anymore. I had to pay full price...