This is annoying so I just use fresh browser profile every time I encounter such site, i.e. have a short-cut for:
$ cat ~/bin/chrome-new
#!/bin/sh
TMPDIR=`mktemp -d /dev/shm/chrome-XXXXX`
google-chrome --user-data-dir=$TMPDIR --no-first-run --no-make-default-browser "$@"
rm -rf $TMPDIR