I've only had this problem on a few occasions, but I believe the older I've gotten, the bigger the problem has become.
After staring at computer screens for 9 hrs a day for almost 25 years, my eye sight has taken a beating. I USED to have 20-15 vision when I began working with computers. Now, I find myself needing reading glasses at work, and when reading fine print. I also believe that my "night vision" isn't what it used to be.
Both of these factors have resulted in a problem at the clubs. When it comes to getting my money out, I sometimes have a hard time differentiating a particular bill's denomination. This became especially apparent during my last club visit. Either the VIP area was darker than it used to be, or my dancer knew the exact place to sit that is darker than the rest in the VIP room, because I thought it was A LOT darker than I'd ever seen it there. It seemed that every time I pulled out my wallet, I really had to study the bill to make sure I was pulling out the correct one. Even still, I mistakenly pulled a $10 when I meant a $20, several times (hopefully, I didn't make that mistake in the other direction).
I always have my wallet organized by denomination which usually helps. However, my problem usually isn't at the beginning of a visit. It usually rears it's ugly head when I've got a wider variety of bills in my wallet instead of just having a lot of 20's. Also, it doesn't help if I've had a few drinks.
Anyhow, does anyone have a good system for being able to discern the value of the bills easily in the dark?


Once I stage-tipped a girl with what I thought was a $1 but, later, when I worked it out at home (I always work it out afterwards at home; I'm accounted to the penny in every way 100% of the time, thank you Quicken!) I realized I had tipped her a $20 under her garter. She had given me a huge smile and had attended to me rather rapidly after her set, and golly gee I'd WONDERED what I'd done to deserve such attention. :)