A comment I get a lot from quilters is, “My scraps aren’t pretty like yours.” The truth is I have ugly fabric in my scrap bins. The only difference is I know how to use it so it doesn’t make my quilts look ugly. Let me give you some tips.
First, while I feel every fabric has a place in a quilt. You can’t combine every fabric in the same quilt. It’s like the soup you make to clean out the fridge. Lovingly called that soup you hate at our house. While you may include leftover veggies and meat, you don’t include the leftover chocolate cake. The same is true with your scraps. So if you ugly fabric is a bright print don’t include it with your rustic and homespun fabrics. Instead join it with batiks and other bright prints. It will fit in and play well. You won’t even notice it was a fabric you thought was ugly.
Next follow Bonnie Hunter’s advice. “If you think a fabric is ugly you just haven’t cut it small enough yet.” Try cutting the fabric down. Use it for star points. Small bits of ugly fabric also work well at the end of a spider web or string block. Speaking of string blocks a narrow strip of “ugly fabric” will blend nicely. If you use the above rule. This post will give you more ideas for small ugly fabric scraps. 
Another idea is to have a little fun with friends. Try having an ugly fabric challenge. Either divide up your ugly fabric or swap and then see what everyone comes up with. You could pool money to give to the winner or come up with another prize.
The thing to remember when using “ugly” fabric in your scrap quilts is that value matters more that color. So don’t worry about that print you don’t like. Instead view it as a light, medium or dark fabric. If you surround it with like value fabrics it will blend in and no one will notice the print. Instead it will add to the harmony of the quilt.
I hope this gives you new eye for your ‘ugly scrap fabric. Have fun playing!
Another suggestion for the ‘ugly’ fabrics — turn it over and use it anyway. I’ve done that a number of times and it worked beautifully in the quilts I used it in. It just makes the ‘ugly’ a little bit less obvious as it appears to be more washed out. I am way too frugal not to use up all of the fabrics, and with your suggestions & remembering you can turn it over and still use it it will often add a little something extra to the quilt you’re working on. Just like my wrinkles are ‘character’ lines to me, ‘ugly’ fabrics used correctly adds a bit of character, too.