Cold solder joints, or "crappy" solder joints, aren't electrically or structurally stable. If a joint doesn't appear perfect, it's probably cold. Reflow the joint by applying the iron and allowing the solder to flow through the junction again.

Cold solder joint

Same joint, reflowed for perfection

If ever a joint seems out of luck, feel free to start over. Use the solder sucker to remove the solder in the joint, then reheat the junction and re-add the solder.