The Shikker Dovid has been learning some of the second chapter of Bava Metzia. On page 23b (at the bottom) the Talmud makes a statement: A young torah scholar may “change his words” (deviate from the reality, Gd forbid lie) when asked about three things:
1. Does he know a certain tractate of the talmud-ie his learning
2. Questions of intimacy and marital relations
3. The hospitality of others.
The first two are understandable, clearly one need not brag about his learning and secondly one need not discuss intimate things with others. But why hospitality of other? The Shikker Dovid has puzzled over this and finds only one solution.
The third idea, hospitality is different because it relates to another person, not oneself. The lesson is that one should guard another person’s privacy, modesty and humility as if it was his own. The same way we can change our words so as not to divulge things about ourself, one can change words so as not reveal things about others. We must guard other peoples privacy the same way we have the right to guard our own privacy.
ShikkerDovid 
wouldn’t it be lashon harah to comment on another’s hospitality. even if he were to praise his hospitality, others might preceive it as haughtiness and not graciousness. also, perhaps if the person is not viewed as generous, it could be because he shows his generosity in other forms, is very modest about it, or simply can’t afford it.