First, for those in the market for a slipcover, check out www.uglysofa.com. They have beautiful and affordable slipcovers. They carry brand name slipcovers at unbeatable prices. Believe me, I've looked at the other places. And I was not paid to say this, just found them and saw how awesome they were.
The second thing I came across was on Pinterest. I found a tutorial on how to clean a microfiber couch. (Update 8/13/15: the link to the original tutorial is gone.) It was really my lucky day because that's exactly the type of couch I have. So I figured I would give the cleaning a shot and if that didn't work, I could always buy one of the great slipcovers I found.
I made a list of all the supplies I would need and headed out to Walmart to get them. I couldn't find white scrubby sponges like she recommended but I found brown, which match our couch so I grabbed them. I had no trouble with the rest of the supplies.
A spray bottle, rubbing alcohol, soft scrubbing brush like pictured, scrubbing sponges (ideally white to prevent color transfer).
Pour the rubbing alcohol into the spray bottle and spray the affected area of the couch. Use the scrubbing side of the sponge to scrub the dirt off of the couch. Then use the soft bristled brush to rub the nap of the fabric back up after it has started to dry. It will help restore the original softness of the fabric. Try not to over saturate the fabric because it can leave "water ring" like spots and only clean in small sections at a time.
I didn't notice until I posted it but I had a nice glass of wine in my supplies picture. It wasn't mentioned in the supply list but it is a nice thing to have if your couch is as dirty as mine. You are going to be doing a lot of scrubbing and you will sure need it for your breaks. Warning though, open a window or two if you can, the smell of rubbing alcohol is VERY strong!
So this is my dirty, ugly couch cushion before:
And this is my lovely, almost perfect couch cushion now:
I think I can live with it awhile longer.