Opinion about this solder job from supplier

[john2k]

I purchased a PCB from china which is for my car head unit. A modification is required where 4 SMD resistors (0805 size) need to be moved around (2 from each side) this allows it to work as RHD. The supplier in china that I purchased it from said they can do the modification. Having just taken delivery of the PCB boards and looking at the area where they did the resistor move, it looks a little bit messy but mainly what looks like flux residue. But what is worrying me a little is trying to zoom in to the resistor to take a pic, the writing on the resistors seem a little burnt out or maybe they are covered with flux. I'm not sure. So i'm a little concerned if those resistors they de-soldered and re-soldered are still ok. So wanted some opinions based on the pics below, do the resistors look like they will be ok? is there a way to clean this without risking anything on the PCB?

[ataradov]

Hard to tell. Given the presence of flux, it looks about as expected. Clean up the flux and see if it looks any better.

[john2k]

What's the best way to clean it without risking any damage to the board?

[coromonadalix]

IPA   isopropilic alcohol ....    for me, i'm  more aggessive with acetone  loll, but never touch plastic and dont smell it

sloppy job   and   use a nail finger  to gently scrape off some solder left overs  on the pcb

[Microdoser]

Hard to tell, is it possible to get clearer pictures?

Seems to me that adding a little flux and reflowing them would make it look neater, but from the look of things it's electrically and mechanically sound.

It looks as though what was required has happened, they moved some resistors by hand. Personally, I would have done the modification myself if I were concerned about aesthetics post-modification.

[Gyro]

It's a good example of things to consider when asking a vendor to do such modifications. Hand rework with an iron is never going to be as neat as reflow - and you don't want them to reflow the board twice. They're also going be doing such reworks at speed. More specifically, if you want them to clean the flux off, you have to explicitely state it, otherwise they won't bother.