One of the biggest scams IMO is to offer say
20GB Web Space but only allow you 10GB Of Traffic
So to fill your space you will go over quota
and either be suspended or charged (Thanks 1&1 for a $160 Bill for Traffic - Few years ago now).
They may use bigger numbers now, but web space and bandwidth
is an easy catch for a web host.
1&1 can offer x15 mysql's for example
but you can not exceed 100mb PERIOD. (Regardless of all the space in the world, you cant merge your 15 sql's into one)
The data base will run but soooooo slowly.
hope that helps