When I think of unhealthy, "bad" support, I think of support that hinders my growth (or someone else's). For me, this is unwanted support, too much support with things I want to and can do for myself, more support than what I need offered in an aggressive way (as if I had to accept it).
For me, good support is needed support for a good-quality life, support I am ready and willing to receive, support with things I can't do by myself. What I perceive as healthy is support offered and only given when I've said yes, not support shoved down my throat whether I welcome it or not.