How can I get images placed in InDesign to stay 100% scale

The thing is, I work in sort of frenzy. I want an option where I can just check everything globally at the end. I didn't do any more work on this Sunday but I'm going to try the object styles & see.

Perhaps this “report” will do what you want:

Or perhaps a tab delimited text file that you can open as a spreadsheet and sort or filter on the Scale X/Y % columns:

// LinkExport-Pro_1a.jsx 
//DESCRIPTION: Exports some information about placed images in the active Document into a textfile in the same folder as the document.  
// The values are tab-separated, so that the content of the file can be copied to Excel via Clipboard. 
// The exported textfile has the ending ".txt". 
// Script by Martin Fischer (www.hilfdirselbst.ch)
// 
var myDoc = app.documents[0]; 
if (myDoc.saved == false) 
{ 
  alert("Error.\rYou must first save your document."); 
  exit(); 
} 
var myDocName = myDoc.name.split(".indd")[0]; 
var myTXT_File = myDocName + '.txt'; 
var myPath = myDoc.filePath + "/"; 
var myCreator = "R*ch";  
var myType = "TEXT";  
var theFiles = myDoc.links; 
var myData = "link\tpath\tpage\twidth\theight\t% vertical\t% horizontal\teff. PPI\r";  
var f = new File( myPath + myTXT_File );  
f.open( 'w', myType, myCreator );  
f.writeln( myData );  
for (myCounter = 0; myCounter<theFiles.length;myCounter ++ ) {  
  var myBounds = theFiles[myCounter].parent.geometricBounds;  
  var myWidth = Math.round(myBounds[3]-myBounds[1]);  
  var myHeight = Math.round(myBounds[2]-myBounds[0]);  
  var myScaleVert = Math.round(theFiles[myCounter].parent.absoluteVerticalScale); 
  var myScaleHori = Math.round(theFiles[myCounter].parent.absoluteHorizontalScale); 
  var myImagePath = theFiles[myCounter].filePath; 
  // WARNING if vertical scale is different to horizontal scale 
  if (myScaleVert != myScaleHori) 
  { 
  var myWarning = "% vertical is not equal % horizontal"; 
  } 
  else  
  { 
  var myWarning = ""; 
  } 
  try  
  {  
  myPPI = (theFiles[myCounter].parent.effectivePpi); 
  }  
  catch (e)  
  {  
  myPPI = 0; 
  }  
  var myClass = theFiles[myCounter].parent.parent.parent.constructor.name; 
  // image placed on page 
  if (myClass == "Page")  
  {  
  myPage = theFiles[myCounter].parent.parent.parent.name; 
  }  
  // image embedded 
  else if (myClass == "Character") 
  { 
  try  
  {  
  myPage = theFiles[myCounter].parent.parent.parent.parentTextFrames[0].parent.name; 
  } 
  catch(e) 
  { 
  myPage = "versteckt im Überlauf"; 
  } 
  }  
  else { 
  try  
  {  
  // image placed outside the pages 
  myPage = "Spread of " + theFiles[myCounter].parent.parent.parent.pages[0].name; 
  }  
  catch(e)  
  {  
  // don't know the page where the image is placed 
  alert ("Class: " + myClass + "\r" + theFiles[myCounter].name); 
  }  
  }  
  myData = theFiles[myCounter].name + "\t" + myImagePath + "\t" + myPage + "\t" + myWidth + "\t" + myHeight + "\t" + myScaleVert + "\t" + myScaleHori + "\t" + myPPI + "\r"; 
  f.writeln(myData);  
}  
f.close(); 

I suppose there isn't any fix, which is what I suspected. UI flaw...

I couldn't tell from your original post if the problem is the graphic's horizontal and vertical scales don't match, or you need both to be exactly 100%?

If the idea is that you need the artwork to be exactly 100% in order to get an optimum resolution for the press output, that is not true. An image at 100% could have any output resolution (Effective Resolution in the link info panel). Also, both the image and its parent frames could have different scales, which would combine to affect the output resolution.

A simple script could force all of the document's graphics and their parents to be 100%, or have matched horizontal and vertical dimensions. I can post one if you need it.