The old man in the story uses the terms "glove cleaner" and "life cleaner" as euphemisms. Obviously, he doesn't want to use the word "poison" too openly, so he uses circumlocutions to hint to his customer that he might want to use something to get rid of his beloved in the future. The reader learns in the course of the narrative that the love potion only costs one dollar, while the "chaser," the "glove cleaner" or "life cleaner," costs five thousand dollars. The old man is confident most of the young men who buy his love potions will be back to buy his poison at some time in the future. He explains to Alan Austen:
"I look at it like this," said the old man. "Please a customer with one article, and he will come back when he needs another. Even if it is more costly. He will save up for it, if necessary."
"And how much," said Alan, "is this wonderful mixture?"
"It is not so dear," said them old man, "as the glove-cleaner, or life-cleaner, as I sometimes call it. No. That is five thousand dollars, never a penny less. One has to be older than you are, to indulge in that sort of thing. One has to save up for it."
In other words, the old man makes all his money off the poison, and his young customers who buy the love potion will not be able to afford that lethal "chaser" until they have reached middle-age. The old man obviously has a very cynical view of love. He seems to believe that love leads to marriage and marriage—for many people—becomes so unpleasant that they will do almost anything to get out of it.