The 'downside', or 'work', of using multiple unique DEAs (Disposable Email Addresses)
is having to maintain some system
by which you're email client software can generate messages with all those
different DEAs in the appropriate From: fields.
Different desktop email clients have different approaches to this situation;
and online browser based interfaces to remote email accounts offer potential as well.
Considering multiple different types of email address usage:
Announcement List Subscription
You subscribe to an announcement list, for which you only need to put each unique DEA
into the From: field of outgoing messages on subscribe and unsubscribe messages;
2 to 4 times in the lifetime of the DEA, depending on confirmation policies.
For this purpose, it's relatively easy to use a unique DEA for each subscription.
Each of these DEAs can be aliased or forwarded to a single mailbox account
and there filtered into separate 'folders' on the client MUA.
See note below about using Catch-All addresses.
Active Discussion List Subscription
For dicussion lists where you need to use your DEA in the From: field of every message you post,
it's more convenient to group several subscriptions under a single DEA.
In my experience, most list subscriptions do not generate a lot of spam;
the cost-risk-benefit analysis is that the probability of a DEA being compromized
is less than the expense of maintenance; and the cost of replacement is minimized
by grouping fewer than a dozen subscriptions into a single DEA.
Passive Discussion List Subscription
These are subscriptions to discussion lists to which you seldom post.
For these, a service such as MailShell
are very useful; you can automatically forward or POP the mail to your desktop for reading;
and when you care to post, it's easy to do so from the browser interface rather then from your email client.
Registrations, for products, services, online forums, etc.
These are mostly one-way communications, and therefore lend themselves to unique DEAs,
all of which are aliased or forwarded to a single mailbox account.
You'd like to be able to trust these outfits, but at the end of the bubble their collection of email addresses is of marketable value to them and others willing to purchase.
Temporary Use Correspondences
For these I use a common DEA which I'm willing to discard and replace as soon as it is compromized;
and never remember or care about how I've used it. Either remember it, or write it in a convenient place (on monitor),
and use it with all correspondence for which you have no care of the future.
The "Dave Null" account. Mail which comes to this account is rejected or deleted immediately; you never see it.
You don't have to change this address very often.
We use the name of the family pet, and/or variations thereon.
You can expand the usefulness of a 'trash' account by not deleting all mail to it,
but by only checking it immediately after you've used it in cases where you may need to
read and respond to a 'confirmation' response.
Everybody's business relationships are different; and they are all special; so there is not a likely 'one case fits all' solution.
Every business needs personal correspondence, and also publicly published addresses.
I've developed the following solution. Printed email addresses (cards and letterheads) are in the form of firstname.lastname@example.org
which is set up as an account which auto-replys with a message which reads something like:
The current active email address for this user is [current_id]
You should modify your address book to use this current address which will remain active indefinitely, until it is abused.
Also, you'll need to resend your message which triggered this auto-response.
For [current_id] I use a dated form of something which I can remember.
Personal Correspondences - General
The trick with these, which makes them different from the more closely held addresses,
is that some crony or another is going to add it to the To: field along with several other of their cronies,
and the darn thing gets forwarded around the 'Net indefinitely. Oh well.
The solution here is quite like the solution for business use.
When an address has been compromised, you have the decision in both cases
of turning the old address into an auto-ack (alias it to your permanent auto-ack), or deleting the account.
Personal Correspondences - Family
These are your closest associates who don't care what your address is; they'll put it into their address book as often as you ask them to, and as often as you change it.
a note on creating DEA names:
I like to incorporate a "date stamp" into my DEAs, which will clue me as to the date when I created the address or account.
Another benefit of "date stamps" is that they ensure uniqueness; you don't have to wonder whether or not you used this address earlier.
For this purpose I use the form of 'ymdd' by which 3b14 represents 14 November 2003.
For my "Temporary Use" address, I still have 'tu2a28' which happens to be easy enough to remember.
There's no point in getting TOO complicated about this.
a note on using "Catch-All" Addresses:
These appear convenient, but are not good practice. If you use them, and want to destroy (dispose of) an address, you have to accept mail to the disposed address and then delete it, and you have to configure to do so.
The preferable alternative is to configure each address you wish to use, by creating it as a separate mailbox, a 'forward' to another account, or an 'alias' to another mailbox.
Then when you dispose of an address, it is no longer accepted by your mail server and remains somebody else's problem.
Furthermore, a "dictionary attack" will be most painful when applied to a domain using a "catch-all" account.
 I've been a very happy user of MailShell for a long time now;
and have no other or commercial interest in promoting them.