Would be more wary of elder teens' sleepovers - as an eighteen year old I regularly 'crashed' at a friends, often along with 3 or 4 others due to the fact we'd go out and get stuck with no buses.. Her mum worked nights, told us to come and go as we pleased , and so we essentially had a free house.
I often wonder what her mum thought of us sleeping in her bed without permission (well, the floor was uncomfortable so host told us to use the bed!!), borrowing toiletries, eating all the good food for breakfast.. I loved it - we would stay up til the back of 3 often with a chips and ice cream run at 2am.
We did things however that if I had DCs who did them, they would never host a sleep over again - my friend tried to teach me how to produce fire from inhaling lighter fuel and then igniting it in your mouth.. and host friend warned us the cat wasn't well so to leave it in the kitchen with laminated flooring.. Drunkenly we thought it would be cold and so allowed it to go onto the bed..
Also went to a friend's house at 15 - at 9, her mum said she was off to the pub and didn't come back til 2 or so. Had never been alone at night before, we happily watched Pyscho and didn't sleep a wink.
All the sleepovers I had at 11,12 were much tamer and nicer affairs involving playing with friends guinea pigs, barbies and making popcorn.
So yes. I would be far warier of allowing teenage DCs to have sleepovers at home. Unless you are willing to hang around and keep an eye. FWIW I am normally a very quiet and shy person but at that age, the combination of alcohol, friends and an 'empty' wasn't conducive to good behavior!!