I convert any images I edit in PS to "sRGB" before saving, but this doesn't solve the Firefox/Safari recognition of color profiles issue. I love Safari, but most people viewing my photos (on flickr for example) are using a PC and the colors look so much more muted and washed out on IE and Firefox.
This is because out of those three browsers (IE, Firefox, Safari), only Safari actually supports embedded sRGB color profiles.
This post of mine has a link to some information that explains it in more detail.
As far as what I meant by the images not being converted properly, if they are in any color mode other than grayscale, then they will retain color information and are not a true "B&W" image.
Here's an easy way to tell:
Take your image (one of your sRGB "B&W" ones) into Photoshop
Go to
Image>Adjustments
If you see anything there about color or saturation, then the image isn't true B&W. It does hold some color to it.
Depending on a person's monitor calibration or the browser or viewer they are using, it could show some reddish, brownish tint.
If it were actually Grayscale, then those items would not be accessible in the Adjustments menu.
This image shouldn't show as having any hue or tint to it, no matter what you viewed it with... unless your monitor's calibration was way off.