Why are their white 'shadows' on dark clothing?

If your using powder detergent switch to liquid.

Too much detergent, it doesn't completely rinse out well, and spots where it concentrates get this after drying.

Another possibility is that you might have really hard water, and your detergent isn't fully integrating with the wash water, Don't overfill your washer with clothes.

Try running an hot wash cycle (without clothes) and one cup of vinegar - this will remove any build-up of soap residue either in the tub or pipes (it'll also remove any "old soap" funk from the machine).

If you have a high efficiency washer there have been many problems with them.

https://www.shopyourway.com/questions/1172099

Could also be underarm deodorant. My beloved can't seem to put on a shirt without smearing the stuff on his clothes. Try spray 'n wash before laundering.

no problem with my printed tops/shirts, just solid color dark capris and pants. I just ran a cup of vinegar in a hot wash like previous poster advised--hope that does the trick!

thanks to all.

I only get that when hubby or kids put too much in the machine and when they are washing dark sheets and blankets. I think all the soap suds don't get rinsed out completely. I have never seen it on anything but dark sheets, dark blankets and dark clothes, it probably wouldn't show on light colored things. The vinegar should work as it does cut the residual soap. You could also try using the extra rinse that most machines have and see if that helps. It may not be your machine, try smaller loads of the dark heavy clothes, could help. I only use liquid soap cuz of having some soap not totally dissolving years ago. If you go the new route, research if you want the newer style or not. I have had HE since shortly after it came out, some people are lamenting getting them due to not having an agitator anymore. I see no difference in cleaning clothes, just the way sheets and blankets roll together into a donut. Mine is a top loader, not front loader,( won't ever have a front loader) a person has to bend enough to get things out of the dryer.

Never overload the wash cycle, your clothes need to swish around. Switch to liquid detergent and use only the recommended amount for each load. I also suggest using cold water. Wash dark clothes by themselves. Best of luck.