If, by deep clean you mean neutralize a pipe, it's going to take a bit of work. Here's what I do and it's a "no shortcuts no bullshit" approach.
1. Start by paring back all cake until it's barely a veil over the wood - I recommend glass paper wrapped around a piece of shaped doweling, or failing that a Pilot marking pen, to do the final sanding.
2. Clean out the shank airway - this may involve using a drill bit or a reamer to clear out any cake building in the airway. Use shank brushes to start, with Everclear or the equivalent alcohol and scrub, rinsing out the brushes repeatedly, to loosen, soften and remove most of the the surface deposits, then move on to scrubbing with tapered bristle brushes, however many it takes, until you're seeing the barest bit of brown on the bristle brush. Clean out the mortise, every bit of it, using dental tools if necessary to get deposits out of the corners. You want to see clean wood in the airway and the mortise. Scrub out the mortise walls thoroughly, using doubled over wads of tapered bristle cleaners that fit snuggly against the walls of the mortise and keep scrubbing until nothing is left to come off into the wad.
3. take a pipe cleaner, dipped in alcohol and insert it through the stem and leave it there for an hour. Then use it to scrub the interior of the stem. Repeat. You may need to repeat many times before the stem is actually clean inside. Don't forget to carefully scrub out the slot as well. it takes time and a good soak to loosen up deposits in the stem.
4. S/A treatment for the chamber. Don't be surprised if you need to do this more than once. You can substitute cotton balls for the salt.
5. Clean out of the airway. You thought you already did this? No, you only did the first step. Lighten moisten a fluffie pipe cleaner, insert it in the shank airway and hang the pipe, stem down, and forget about it for a few hours, then scrub to remove further deposits and rancid oils. Do this a few times. Next, lightly moisten a fluffie, insert it in the shank airway, and hang the pipe shank down and forget about it until the fluffie has completely dried out, pulling out rancid oils from the briar. Repeat this until you're barely getting any staining. Do the same thing to the mortise using barely dampened fluffie wads and let dry out. Usually takes 3 to 4 days of soaking and draining tobacco oils.
Or, you can avoid some of this by performing a boiling alcohol retort flush.
If you actually go though all of these steps thoroughly you will have deep cleaned years, possibly decades of embedded crap from the pipes' internals and will have a neutral pipe with no ghosts.
Have fun!
