Really, that should be in all CAPS!
Also, really - just don't even get me started!!!
But one that comes to mind is my great-great grandmother Standley's death certificate. The handwriting was so bad that even Vital Records didn't find it when I had mailed in for it, years ago, even though I knew the exact town and year. Fortunately, Ancestry.com has PA death certificates these days.
But Ancestry.com had it indexed as "Barbara K Slamby", which is a far cry from "Barbara Catherine (Fox) Standley". To finally find it, I searched for somebody with the exact month of death, for her county. This was NOT the first thing I tried, nor the second. Or third. Or fourth...
"Mullins" vs "Mullius" is a pretty typical kind of error. A handwritten "N" can EASILY look like a hand-written "u". EXPECT that kind of thing, as often as not!
You're hardly going to find ANYTHING if you rely on the indices to be 100% perfect. You MUST, MUST, MUST learn to use the available search criteria creatively!!!!! And BE PERSISTENT!