@harding Again, only a suggestion, perhaps we can make this subtle change:

> In each transaction, the spender and receiver each reveal a public key or address to the other person. Afterwards, either person can use the public block chain to track past and future transactions involving the same public key or address, weakening each person's financial privacy.

s/ made with/ involving/ the same public key or address

In any case, unless I'm mistaken, the starting point to track your payment is always either the public key or the address you have provided:

P2SH : Spender can track your address, and then track individual public keys when you spend it.
P2PH : Spender can track your address.
P2PK : Spender can track your public key.