Used Equipment - Safe to Use?
Yes, some parts of used equipment can be cleaned up with a propane torch and would be fairly safe to use, especially for an experienced beekeeper.
Where the big problem lies is in the brood chamber. Here the Queen lays her eggs. Most diseases that threaten the hive health are brood diseases, one of the worst of these being American Foulbrood. This is a spore-producing disease. These spores have been found to remain active for over forty (40) years. If the spores are present on the used equipment, they can multiply and become a big problem.
Old brood comb can be a problem as well. Each cycle of brood will leave behind a cocoon, thus making the cell progressively smaller and smaller, resulting in each generation of bees becoming smaller until finally a point is reached where the Queen refuses to lay an egg in these cells.
Mouldy, white-ish pollen, not fit for the bees to use and too hard to remove, can also restrict the area that the Queen has to use.
The solution for the new beekeeper for the above problems is to start with new equipment, new frames and new foundations. The investment will more than pay for itself in healthy bees and satisfaction to the beekeeper. There is plenty of time to get into second-hand equipment once you get to know what you are doing.