The best swab in use today is the pull-through. Old-fashioned, woolen swabs on a rod are to be avoided as they shed hairs into the instrument which can gradually build up in tone holes and in the pores of the wood.
Swabbing is probably the main reason instruments become blown out. The term swabbed out would be more accurate.
The choice of swab has a big influence on your instruments lifetime and intonation.
Over several years an instrument may be pulled through up to 10,000 times. The tighter the swab fits through the bore, the faster the instrument will wear. The bore diameter will increase and the instrument will become sharper. It is therefore recommended that a low-resistance swab is used, such as silk or microfiber.