Some might disagree, but I feel the same about almost any troop that I can get from a building before I am able to produce (and upgrade) them myself. It is great if you have the space.
Even Frogs (which I love dearly and want to kiss their slobbery little faces!!) are of only limited use at 1 star. Certain situations (enemy setups), they will kick butt! But most of the encounters I fight, they will be too low level to really make a huge difference.
So, if you have some free space and want to throw down a building that produces any type of troop, that is great. I love free troops! But don't feel bad ripping that sucker out when you are in the final stretches of a guest race and need to eek out every available tile. : )