When Miroku needs a place to stay for the night, he usually approaches the residency of a wealthy family, telling them that he senses an evil presence there and he'll exterminate in exchange for something. More often than not, there is no evil presence and Miroku is just using his status as a monk to get free food and a free place to stay at over night. While this appears to be less than holy, Miroku is not without excuse. He's had to live an extremely hard life, knowing that he'll die a horrible death some day. Getting free food and board from wealthy families is Miroku's way of pampering himself. He feels that, because of his status and hardships, a little white lie won't hurt anyone and in some cases, it's rather convenient.
As a Buddhist priest, Miroku shouldn't have to ask for payments in return for things that he does for people, especially when the people he helps the most are poor villagers. By asking wealthy families, he's doing no harm and he doesn't have to pry money out of the hands of people who have little.
As for his abilities as a monk, Miroku doesn't think much of them. While his powers may impress others, it's normal for him. Unlike Inuyasha, Miroku doesn't gloat about his powers or brag about them, which shows that Miroku is actually a rather humble individual. Even so, despite being humble, Miroku is also confident. He's aware of his abilities and limitations and when he's sure that he can take on a youkai and win, he usually comes out on top of things. There are exceptions but Miroku never rushes into a situation where he couldn't handle himself. Again, this is something that makes him much different than Inuyasha.
It's surprising to learn that Miroku is only 19 years old because he acts much older than his age. Perhaps it's because of the curse and hardships he's had to bear, but Miroku has a sort of wise air about him. He knows quite a bit about various youkai which makes him a valuble asset to the team and he also knows a lot about how people work. On many occasions, he's given Inuyasha advice on how to deal with Kagome and Kikyou. Miroku's intellegence also shows through on how he can think up various plans and tricks to get what he wants and he's got a lot of wit about him. He can usually see through others fairly well and not much gets past him.
Still, as mature as he may act, Miroku doesn't really go out of his way to act wise. He's playful and doesn't really want to be too mature, even though he's quite capable of being so. This is indicated by his letchery and his somewhat mischevious nature.
On a lighter side, Miroku is a very determined individual, to the point of being rather stubborn. When he sets his mind on something, he doesn't turn back. This can be dangerous in some situations but as already stated, it's not often that Miroku gets into a situation where he knows he can't handle himself. Still, he's very optimistic. Despite the fact that he has a curse that will eventually kill him, he's filled with hope. Hope that he'll come across Naraku and kill him, putting an end to the kazana for himself and for his future family. Joining with Kagome, Inuyasha, Sango and even Shippou only strengthens his determination and certainty that he will destroy Naraku. He even accepts the fact that if he dies, it's his destiny... but he's not willing to sit down and take it. He'll fight until the very last day if he has to, which makes him very courageous.
It's not often that people see the caring side of Miroku. He may have no problem using rich people to satisfy his needs and he may be a letch but when it boils down to things, he cares. He won't hestitate to put his own quest on the side to help out villagers in need and he always takes the time to hold memorial services for those he comes across in his travels who have died. Deeds like this often get overlooked by his letchery and delinquency but being recognized for his good deeds isn't something Miroku strives for. He knows that he's done something good and that's all that he needs.