Dark stains on t shirts

[TopperHarley]

(Sorry boring question alert but...) my t shirts keep coming up with dark blotches on the front. Like the same colour as the shirt but darker. I've tried the usual stain remover, hot wash etc but they aren't shifting! Any idea how to get rid of them?

Are you using fabric softner? This can sometimes cause dark stains, especially if you use too much.

Oh really? That's interesting. It could be that as my partner likes it and I do tend to lob it in without measuring Is there any way to get rid of them?