Alice is Bob's master. She could be a master of anything, from martial arts to cooking, anything that involves having a teacher. Bob is very thankful to Alice, since her teaching was invaluable. Perhaps he has more to be thankful for: maybe Alice actually raised Bob, or gave him shelter. Whatever the case, Bob is very thankful to Alice and would do anything for her.
Mooching Master refers to a very particular type of teacher-student relationship: the student is indebted to the master and the master takes advantage of it for personal gain. This is not merely the master asking for money, that'd be too simple. The master actually asks for things that go from annoying to illegal to even life-threatening. But the student owes so much to the master, he feels obligated to comply out of a desire to honor her.
This trope is almost always played for laughs, even in a serious work, and the master is usually not actually malicious. This doesn't mean her mooching is harmless, though, it can actually make the student get in loads of trouble trying to please his master. And the teacher, while she might be teaching the student with her antics, is, when all's said and done, genuinely taking advantage of him to a degree.
Compare Wax On, Wax Off, where the chores the student is performing are actually genuine teaching tools. Trickster Mentors are very fond of this trope. The Svengali is a more malicious version, hobbling their students growth to continue to take advantage of them. Compare Fair-Weather Mentor, who exploits their students for accolades instead of money.
- Mob Psycho 100: Reigen is a Phony Psychic who keeps his ghost exorcism business afloat because Mob, a very gifted Psychic Child, thinks he's a expert. Reigen hands off all the work to Mob, under the pretense of it being below him, and pays him almost nothing.
- In Ranma ½, we have ancient grandmaster Happosai, and of course Ranma's own master(and father) Genma. It should be noted, though, that Ranma himself is an equally enormous mooch, so maybe he actually did learn something?
- General Cross Marian from D.Gray-Man abuses his student Allen by making him gamble to pay off all his master's debts. The anime makes it worse, and takes it Up to Eleven when they do a filler-Episode 27: My Mentor General Cross. Whereupon, Cross has Allen doing slave labor, asks him to catch a lion for him, and corners him in alley ways to take his money.
- Yuuko from×××HOLiC does this to Watanuki accidentally. She has him do all the housework for her, buy her booze, be the Chew Toy for her spiritual tasks, without realizing she's teaching him and training him to eventually replace her as the shopkeeper.
- In the lead-up to the Indigo League in the first season of Pokémon, the team caught wind of the fact that Bruno, one of the Elite Four, was training up in the nearby mountains, so Brock and Ash sought him out for his guidance. When they found him, Bruno agreed to teach them what he knew, so long as they obeyed his instructions. He then got Ash and Brock to carry water, chop wood, and carry heavy rocks uphill, which Ash and Brock assumed to be lessons of the Wax On, Wax Off variety. Turns out Bruno was just getting them to do some heavy lifting for his campsite, and he had no mystical secrets to offer.
- Chop-socky kung fu movies are LOADED with this kind of character. The old Shaolin master ordering his student to get him food and booze is practically a character type by itself. Examples include The Miracle Fighters and Shaolin Vs Lama.
- Tenacious D in The Pick of Destiny: JB thinks Kage is teaching him how to rock via Wax On, Wax Off, but he's really just cleaning up Kage's house.
- Played with in The Grifters. One character has a flashback to asking an old Con Man to teach him how to grift. The conman tells him to give him $10 and he'll demonstrate. After putting the money in his pocket, he says to come back tomorrow, "and I'll take you for another ten."
- He has the capacity to be nurturing, but Professor Horace Slughorn of Harry Potter sifts through and lavishes attention and extra help on the students he believes will go on to fame, success and fortune; he can then enjoy receiving attention, company and correspondence with prize-winning politicians, professional athletes, researchers and powerful witches and wizards of all kinds. He enjoys the implication that he can shape the decisions of these people and that he's influential enough to get fat on gifts from members of his Slug Club.
"Horace," said Dumbledore, relieving Harry of the responsibility to say any of this, "likes his comfort. ... He has never wanted to occupy the throne himself; he prefers the backseat—more room to spread out, you see. He used to handpick favorites at Hogwarts, sometimes for their ambition or their brains, sometimes for their charm or their talent, and he had an uncanny knack for choosing those who would go on to become outstanding in their various fields. Horace formed a kind of club of his favorites with himself at the center, making introductions, forging useful contacts between members, and always reaping some kind of benefit in return, whether a free box of his favorite crystallized pineapple or the chance to recommend the next junior member of the Goblin Liaison Office." Harry had a sudden and vivid mental image of a great swollen spider, spinning a web around it, twitching a thread here and there to bring its large and juicy flies a little closer...
- Mildred accuses Charlie of being this to Amita, in NUMB3RS. She raises a couple of fair points about how he uses Amita's time, attention, research, and resources for FBI work. This leads to Amita carefully distancing herself . . . a little.
- In Arrested Development, Carl Weathers offers to give Tobias acting lessons, but he ends up talking more about getting free food than actually teaching.
- House. Give him students and he will send them to get him cable. And donuts.
- Astrid, Rorona's alchemy master from Atelier Rorona. Right at the beginning of the game, her workshop is in danger of being closed and she gets commanded by the king to either do assignments she's requested or forfeit the shop. What does she do? She changes the workshop's name to Rorona's and saddles her with the job. And throughout the game, she's constantly ordering Rorona to do near-suicidal tasks while also treating her like crap, always running from her responsibilities by throwing them on Rorona. Rorona ends in tears constantly at the stuff she does. It's played for laughs, really.
- In the Raidou Kuzunoha games, Raidou's boss, Narumi, lounges around the headquarters of his detective agency while his apprentice runs all kinds of dangerous errands for him. (He's not a bad guy, though, and does get a bit more involved in the case in the second game.)
- In the tie-in novel, Raidou Kuzunoha vs. the Dead Messenger, this trait gets greatly exaggerated, as Narumi not only makes Raidou handle agency business by himself but keeps Raidou home from school to do his (Narumi's) housework, spends the money he's given for Raidou's upkeep on fancy new clothes, and threatens to kick Raidou out if he doesn't show proper gratitude.
- Even in the first game, it's revealed Narumi is a serious case of Brilliant, but Lazy - he's used to fine dining but absolutely loathes work, and winds up racking a significant tab on several joints. That being said, both the first game and the Raidou manga make it very clear that, lazy as Narumi is, he is no stranger to danger and is a Badass Normal capable of infiltrating the Subterranean Shipbuilding Facility (which at the time was filled with demons he could neither see or damage and Special Forces Units), enduring hours of the Jack Bauer Interrogation Technique by Navy thugs and dealing heavy damage to Raidou's opponents. Additionally, he is a competent detective. He's simply too lazy for his own good, and he's not above abusing the contacts Raidou provides for him, but ultimately his interests lie solely with him, as seen when he feels he won't be able to pull off the above mentioned infiltration and carries it out himself.
- This is Rean and Sara's relationship in The Legend of Heroes: Trails of Cold Steel. Rean, the student, has to put up with a lot of things from his master, Sara. Some of it is basically Rean helping out the student council on jobs she should be doing herself, investigating the old schoolhouse, and having to reconcile his other classmates with their tense relationships.
- A couple of Looney Tunes shorts feature a fat, lazy cat named Dodsworth, who passes himself off as a teacher and has his young pupil do all his mouse/bird catching for him.