Experts say (and I agree) that all images posted to the Web should be sRGB with no ICC profile (the profile is not needed since sRGB is the default on more or less all systems); AFAIK such images should appear the same in different browsers. If you post an image using a low-dynamic-range format (e.g. JPEG) with a non-default colorspace (e.g. AdobeRGB), it will either be displayed wrong (in non-color-managed browsers) or it will lose color accuracy (possibly introducing banding) when the browser converts it to sRGB.

That's all nice and geeky, but those images don't look as good in Chrome as they do in Firefox.

My point is that those images were probably converted wrong, so of course they look bad.