You can most definitely 'chroot' into a (mounted) filesystem meant for a different architecture and do some meaningful work, you just need the right tools.
Have a look at PRoot, which is a user-space implementation of chroot, mount --bind, and binfmt_misc: http://proot.me/
Together with QEMU's user mode emulators, you're all set.
Although you usually cannot perform a 'full' boot (i.e. starting init and services), it is good enough to run some binaries from their 'natural' place, with access to all their configuration files, including some that are bind-mounted from the 'host' system, etc.