High chance of messing up the makeover.
A successful makeover opens the "Change Appearance" options screen. Here the player can change the appearance of the Sim who had the makeover. The customer will be pleased and, if it was not offered for free, pay for the makeover.
Sometimes, the customer might receive a successful makeover even if the change appearance screen doesn't appear, so basically they won't really receive a makeover at all, when this oddity occurs.
An unsuccessful makeover displeases the customer and their appearance is changed, usually by receiving a weird haircut or full face makeup. The Sim who did the makeover still gets paid, unless it was a free makeover.
For selectable Sims, this can be undone by using the Change Appearance option on a mirror. For others, it can be undone with the makeover chair. (It may be necessary to apply full face makeup in order to be able to use the option to remove all full face makeup.)
There is a mod which unlocks the hidden face makeup that Sims may get from an unsuccessful makeover. However it categorizes it as lipstick, instead of face makeup like the original.
Another mod exists that unlocks the hidden hairstyles that Sims may get from an unsuccessful makeover. Note that this mod does not unlock the electrocuted hairstyle.
Ug-No-More Makeover StationEdit