It's a mixed view. You have to take into account that the fluff you read features alot of Guard and Space Marine encounters. However in the general "setting" of 40K encounters with Space Marines are meant to be ludicrously rare (discounting those who "share" a planet / system with a chapter, but even then, statistically this is a tiny fraction of the Imperium's population).
The average imperial citizen only hears the tales and the (false) Imperial Propoganda / Rumours about Space Marines through their entire lives. Imperial Guardsmen are these same citizen, and even for them it's very unlikely to come across a Space Marine unless they are on some Crusade, Happen to respond to aid request, or in a messed up situation enough to warrant the Astartes to show up. To many Imperial Guardsmen, Space Marines are myths, legends and for all intensive purposes - both divine saviours (showing up and kicking ass) and Bad Omens (stuffs so FUBAR the Astartes are needed) at the same time. So when they finally meet and see one there is inevitable awe (Marines are what lions are to cats and adults are to children) but also a natural fear (holy crap why are they here).
Marines on the other hand vary. Depending on chapter, doctrine, birthplace, training and so fourth. Some outright disregard the value of human lives (thinking Grey Knights here) - they only care that humanity as a whole survives; if you need to kill a hundred million, so be it. Most show disinterest (Blood Ravens, Ultramarines) - if they can preserve life they will, if they have to sacrifice it, so is the way of things. Some (Lamenters, Salamanders) hold human life as valuable and try and protect and preserve as much as they can.
Now; when the Guard and Marines meet. It's anyone's guess since it varies from marine to marine. But Generally Marines are built for one purpose - as weapons of war / mankind. They live to fight and die in the name of the Imperium. They are trained and enhanced to perfection in the crafts of death and have endless strength and stamina, in turn they are armoured and geared with divine weaponry made of the best technologies and mythical artefacts. And to top it off they live hundreds of years to fight in countless battles against uncountable numbers of enemies, spit acid, shrug off life-crippling wounds, have memory absorbing zombie-powers and if necessary can survive in the vacuum of space temporarily.
Guardsmen on the other have none of this; maybe one or two guys live long enough to see an officer Comission and some very rare cases get Juve-Vat treatments, but otherwise the average Guardsmen is just as disposable as a bolt round. Inevitably when you place what is effectively a Demi-God of War next to a Rank and File Solider, there's going to be a clash of personalities.