I have received every rebate I have ever applied for. In over 40 rebates, I have had two problems. One was with Kingston which was resolved by one phone call. The second was with Gigabyte which was a lot of work to get. I ended up making a post over at Hardforum and contacting the CA attorney general about it (and making about 10 phone calls and several emails). It was for $10 but in the end (took almost 5 months instead of the 10~12 weeks promised) I ended up getting $20 instead of $10 plus a $50 Visa gift card, a $25 California Pizza Kitchen gift card and various promo swag (beanies and pens and such).
If you let them take advantage of you, just like many people, they will. First, I only deal with companies that I think are likely to pay. Keep copies (scans) of all submitted material. As for "forgetting" about your rebates, just make a folder called Rebates on your computer and stick everything in there.
Some people on Hardforum were saying it was a waste of my time (to attempt to get my money). I think it was worth it. I asked to get a Visa gift card or a CPK gift card (on top of my rebate) for wasting my time. I was vocal about and got both. Their CS rep contacted Kyle to get my email and they got some person to go on Hardforum to address the issue. I believe a few other people had their problems resolved because of that thread also.
For those of you that just give up on a rebate, that is what they are hoping for. It should only take a small amount of work (like one phone call) to straighten everything out if there is a problem. Even if you didn't keep copies you could claim that you did and I would think that most rebate processors would just OK it instead of going through the extra work of trying to verify it (Kingston did to me when I complained). If there are bigger problems you could post on a heavily trafficked computer forum to get attention. I chose H's motherboard section cause I thought it would cost them sales (which it did appear to do, yet Gigabyte didn't seem to care about it (I informed them of the thread when I made it) until I contacted the CA attorney general). I would have taken them to small claims court if it came down to it and I would have won and been reimbursed for the filing fee, the process serving, my missed time from work and anything else I could justify.
Some of these companies are shady but if you stand up for yourself, I think it would be less hassle to just pay the person complaining because there are so many "sheep" just will to take it in the A