What am I doing wrong if the used grounds in the filter basket are like wet sand? I have a relatively cheap (&lt;£100) espresso machine. Sometimes I find that after making a drink, I remove the handle and find the filter basket has lots of water in, so rather than tapping out a dry, compacted lump of coffee grounds into the bin, I have to wash a sloppy mess down the sink.

Sometimes I get it right, but I haven't worked out what I'm doing inconsistently to make this happen.
I have seen this happen due to the age of the coffee being used. I believe that fresh coffee, something roasted within a week of use may cause the soupy puck you are experiencing. The rule of thumb is if the coffee tastes good, don't work about the puck.