I had a 14-hour layover in Lisbon, on my way from Milan to Boston. At the last minute I decided to make the most of it. I took the subway directly from the airport to the Avenida stop, which is an easy five-minute walk from Hotel Residencial Milanesa. I arrived late and was in something of a hurry. Nonetheless, the place was easy to find and a staff member was there to receive me.
The room was clean, with a synthetic wood floor, double bed, and compact but perfectly serviceable bathroom. Thick curtains kept the light out of the room, and the hotel's position a few storeys above the street kept noise levels low. In the morning, coffee and tea were on offer, but nothing more--which I would not have expected there to be, considering the modest price.
I recommend Residencial Milanesa for the seasoned frugal traveler.