I have read some articles that refer to or show Balwin as somewhat sadistic, for example in one I read that he used to go on excursions and burn, rob and kill Saracen villages and he shows us as a ruthless and arrogant guy. Have you read anything about that? What do you think about it? Do you think it's false?
Admittedly, even though I have collected quite a few resources on the historical Baldwin IV over recent months, I haven't had the chance to pore over them in detail.
However, from what little I have read, I do know that, after Baldwin refused to renew Raymond III of Tripoli's truce with Saladin and decided to resume Amalric's efforts to curb Saladin's growing power, back-and-forth raiding on both sides was rather frequent. And though we would condemn such behavior today, in medieval warfare, it's par for the course. Part of the strategy behind doing such things was not only to obtain valuable (and sometimes scarce) resources, but also to damage the opposing side's economy to make their efforts more difficult. Saladin sacked and looted farms and villages on his way to Jerusalem before the Battle of Montgisard; likewise, Baldwin engaged in raids during the tug-of-war over Jacob's Ford - all of which was likely exacerbated by the problems with famine at the time. Unlike Ridley Scott's depiction in KoH, these battles and raids back and forth across the borders of the Kingdom of Jerusalem and Syria were broken only by very short truces that seem to have revolved around resource availability and temporary interests elsewhere.
Does this make Baldwin "sadistic"? By the standards of his day, no. Any other monarch of the period would have likely made the same choices with an enemy force on their doorstep and whilst in a semi-permanent state of war. Further, we don't really have any insights into Baldwin's reasoning for his decisions because we aren't privy to his personal thoughts on the matter. On top of that, what little first-hand accounts we have all possess their own biases, which was also common - those on the side who performed such raids would see them as clever/advantageous, and those on the side being raided would see them as abominable.
It is interesting to note that, during one of these later defense-testing missions at Darayya, Baldwin apparently threatened the great mosque there, but when the Christians local to the area protested for fear of retaliatory harm to their churches, he promptly abandoned the idea and left.