First off, I do not own Avatar. Not at all. Don't remind me.
Toph Bei Fong was blind but could see vibrations with her feet. This was useful for getting around and fighting and basic things, but not so great for details. When it came to details, she had her hands. Since she was a child she could make out the details on varying items in her home just by feeling them. She would run her fingers over an item, check for textures and other sensations. Was it smooth or was it bumpy? Was it warm or cold? Was it soft or hard? Her fingers usually got it right. However, she never touched anyone's face. She wasn't close enough to anyone on her household to want to get to know their facial features, not even her parents. Well she was never close to her parents anyway. She usually listened to their voices or picked up on their scents to tell who was who.
But Toph was changing. She was no longer in a gilded cage, with people she didn't want to know. Now she was surrounded by a rag tag group of people, each with a colorful personality. The kind of people you wanted to know. She was in close quarters with them everyday, she couldn't tell them apart by smell anymore. They all smelled like sweat and bison. Sure she could recognize them by voice, but the catch was, after being with them all for awhile she was, for once in her life curious to know what those around looked like.
Toph sat in her rock wondering how she could figure out what her companions looked like. Sure she could ask, but the descriptions wouldn't work, she had never seen any colors other than the blacks and grays her eyes were blocked by.
She sat racking her brain, thinking until she remembered. Whenever she wanted to know details, she always touched the object she wanted to know about, felt it, let her fingertips explore until she got a pretty good idea of what it was she was holding. Yes, that's how she'd go about this problem. She would touch each of their faces, and study their features until she knew them. Not just so she could recognize them, but because she wanted to know them.
The question was, would they want her to touch their faces?