While for very short sessions this may be adequate, for relatively long sessions or long-term use of a particular resource (e.g. repeated use of an OnlineCommunity), using a consistent IP address, even if it is not your actual IP address, creates a SerialIdentity that will be used to identify you. This is akin to being a cat burglar that leaves a calling card at every location. If you finally make a mistake and identify real self at one break-in, you will be charged will all your prior break-ins. If you had just not left a calling card, you may get away with only being charged for one.
Therefore, frequently use different proxies so as to make it harder to correlate independent transactions to a single identity. Because this strategy is used so often, switching between proxies is often automated with a RotatingProxy. In reality, a RotatingProxy is actually a full set of proxies. Incoming requests are automatically assigned to a new proxy for each transaction.
There are many such networks. The most common are based on:
In truth, most spammers today use RotatingProxy attacks. The easiest defense is the EditHash.