I've been using Nespresso for some time and, in common with some others, I:
1. To start with always run an expresso measure through the machine (without a pod) into the cup to warm the cup and ensure the pipes are clean;
2. Always run an expresso measure through the machine (without a pod) after I've finished making coffee to clean the pipes;
3. Do run two lungo extractions through the same pod to make an Americano (one that's not too strong)....and I think it works pretty well;
4. Regularly make a strong Americano using two lungo extractions from two different pods, usually a strong one and a decaf one.
As you might gather, I'm not a coffee aficionado but I do like it to have plenty of taste and Nespresso has never let me down.