Lotsa good ways to clean a muzzleloader. As Lewis pointed out, the snake flue on a cap gun can be an issue, but not for me as I only have and use nothing but flinters. Here's my cleaning regimen that's been flawless for too many decades.
When the shooting is done for the day, a few oiled Ballistol (or WD40) wet patches
Immediately go down the tube and the rod left in the bbl, an oiled wet patch wipes down the entire lock. The idea is to get on the BP residue ASAP before it wants to harden and/or do nasty things. When back at the ranch, the real cleaning can begin.
Cleaning a side lock is too easy. First, remove the rod 'n' patch that was left down the bbl and then remove the lock ... yes, unscrew it and pull it off. Remove the flint and its leather. Put the entire lock in a bowl or pail of tepid tap water. Plug the touch hole with a round toothpick and pour tepid tap water down the bbl for about 3/4's to full (doesn't much matter, but there's no need to fill it as it's the chamber and about a foot above that where most of the caked BP residue accumulates).
Allow the gun to stand muzzle up for the water to do it's thing while you return to the lock. Use an old tooth brush to scrub the lock. When it's reasonably clean (maybe a minute tops of scrubbing), shake off the excess, pat off as much water with paper toweling, spritz the entire lock with Ballistol (or WD40) then leave it rest on a paper towel. As a note about spraying Ballistol, I buy small plastic pump bottles and fill with Ballistol as this is cheaper and just as good as buying Ballistol spray cans.
Back to the gun, pull out the toothpick and water will pizz out the touch hole. Use patches wet with plain water (or moose milk - 1:6 of Ballistol:water - or any water soluble oil instead of Ballistol) to clean out the bbl. You will Never ever get cleaning patches to come out perfectly clean because some of the elements of black powder (notably the graphite used) remains in the bbl metal and leaches out onto patches. When wet patches come stained but otherwise clean, run down a few dry patches, and then one good sloppy wet patch with any kinda gun oil. I leave the rod and oily patch in the bbl for storing the gun.
Back to the lock, wipe off any oil residue (there will be some left, which is good), wipe down the entire gun - bbl and stock, screw back the lock onto the gun, reinsert the flint and yer done. If it seems complicated or time consuming, it really isn't. At a leisurely pace it takes me about 15-20 minutes and if I rush maybe 10 minutes. Sure better than cleaning a centerfire bbl of lead or copper wash.
The above is for classic flat face breech plugs. For patent breech plugs, a brush (.22 to .30 caliber) draped with a patch is required to get into that plug's ante-chamber.
I prefer using Ballistol because it's good for the wood, totally non-toxic - all other CLPs are not, and that includes WD40.