The conversation that Malcolm and Macduff have in Act IV scene 3 leaves little to the imagination in the way that they talk about Scotland and what life is like under Macbeth's reign there. It is clear from the language that they use to talk about Scotland and how they depict what life is like there, that Macbeth's reign has not been good for Scotland or its populace in any way whatsover. Note, for example, the following quote from Macduff:
Each new morn,
New widows howl, new orphans cry; new sorrows
Strike heaven on the face, that it resounds
As if it felt with Scotland, and yell'd out
Like a syllable of dolour.
Things have reached such a terrible state in Scotland therefore that it has become a country synonymous with premature death and despair. Note the repetition of the word "new" in the qutoe, refering to the way in which every day that passes brings new deaths to Scotland and everybody suffers as a result. To live in Scotland under Macbeth's reign was therefore to live a life that was desperately uncertain and full of fear. There were clearly no guarantees of a long and happy life with Macbeth's violent reign, as the existence of the "new widows" and the "new orphans" testify. The overwhelming impression of what Scotland was like under Macbeth's reign is captured in the final symbol of a "syllable of dolour": unremitting pain and unyielding misery. No wonder, therefore, that Macduff is so desperate for Malcolm to invade and take back his rightful inheritance. Scotland under Macbeth's rule was terrible for everybody.
There is no doubt as to Malcolm's and Macduff's revulsion for the usurper of Scotland. At the very outset of the scene, Macduff enthuses Malcolm to take up arms and defend his inheritance and birthright. Macduff is outraged to see dead bodies of young men: widows and orphaned children bereft and grieving the loss of loved ones. Their screams of agony rending the air and reverberating to the heavens themselves.
Initially, we sense caution in Malcolm as to his relationship with Macduff. He is suspicious of Macduff because he openly tells Macduff that he has been a close friend of the tyrant and a favourite. His assumption is that Macduff might have arrived in England only to lure the "poor, innocent lamb" into the traitor's snare. He's of the opinion that Macduff may stand to gain by betraying him. He quotes the example of Lucifer, who'd been God's favourite angel and yet was thrown down from heaven because of his rebellious nature. He hints that Macduff too could fall from grace and turn traitor.
There is no doubt that Malcolm feels uneasy in casting aspersion on Macduff, but, that is only to protect himself from being ensnared. He tells Macduff that he must not think of his suspicion as dishonour to himself, for he may be quite honourable despite what he thinks of him.
Macduff is appalled and visualizes the end of Scotland, since its heir and successor, has lost faith even in those men who are loyal to him. He grieves and says that Scotland will continue to bleed and there will be no retribution for the evil and the wicked because "goodness dare not check thee".
Malcolm is aware that Scotland is doomed and each new day sees a fresh wound inflicted upon it. He knows that the tyranny and oppression that Macbeth has unleashed upon its hapless people will not cease unless a greater power is set forth toward Scotland to cower the brute and bring him to his knees.