by writing you mean cursive, right? That's me, all the way. My handwriting is such that I've been asked if I was raised by doctors, or if I'm a med student... but my printing is far worse.

I love your story, R. R. Rat!    I must remember it.

I have a similar situation.  My true signature is unreadable and next to impossible to forge due to a letter I write "backwards". 

When I was in high school, someone stole my check book and tried to forge my signature.  (This person knew me and had seen my signature.)  I reported the theft to the bank and the police.  The police asked me to come down and give them signature samples to use in the event any checks were passed and suspected.  As I gave them the 10 signatures, the handwriting analyst that watched me made the comment that there was no way anyone would be able to forge the signature.  A few days later I was informed that a suspicious check was attempting to be cashed.  The police asked the retailer if the name could be read - specifically the first name.  The retailer reported that they could read the name, so the police quickly reviewed the signature against the samples - quite sure that it was a forgery - which it was.  My account was not affected and the forger was charged and convicted.  I was happy to learn that my dyslexia and difficulties with cursive writing actually saved my bank account!

My signature has both my real first name, which very few people actually know, and a pseudorandom series of squiggles in the last name.. not to mention my last name isn't very common at all outside massachusets, and/or new orleans, so not many would be able to read it, or figure out what it says anyway...
I've never been able to forge anyone's signature(my handwriting is too distinctive in general)... but then again no one yet has come close to mine either.

When I take the time I can make my script legible to people other than me. Otherwise poor Angel Spun would have had a hard time reading my card for the SS gift, LOL.

I can also write backwards, and with my right hand (I'm working on backwards right handed too).. I think that writing backwards has actually improved my forwards writing some.

Funny story about that, actually.

I had a history teacher in 11th grade who insisted that I take notes... Now.. I've got a memory such that notes do me no good, so I didn't bother. She decided to grade us on our notes, to force me to take them... *evil grin of the 7th magnitude*... Come friday, I turned in an exact copy of the notes she'd written on the board, down to her obvious misspellings and bad grammar, completely 100% backwards. I think I fried the poor woman's brain... She never did grade on notes again, though...