Step 1. Open MC and go to multiplayer Step 2. Click on the server that keeps saying "Failed to login: Bad login" and try joining it 3 times (must be three) Step 3. Spam "Refresh" (10-50 times) WITHOUT TRYING TO JOIN THE SERVER Step 4. Log in. If message still pops up, keep spamming refresh until you log in.
People say there are issued. I agree :\ . I have found that My Friends BUKKIT Server and My own have about 1/4 People actually visiting! On 1.7.2 This error does not happen. Or any below versions (I checked until 1.1, I backtracked my server and it all worked but 1.6.4.). I also see that Direct Connect works more often, So if you Urgently really need to go on, Copy the IP Into Direct connect to potentially fix this error until Mojang Gets this patched or Fixed.
Why would they fix a bug that was only occurring for old versions?
Because people still have servers that are on older versions of minecraft, either because the server doesn't want to lost special mods it has that the newer updates have broken or other various reasons.