Each payment you received in the past will require at least 148 bytes to spend in a transaction.

So, for example, if you received 1000 payments of 0.0001 BTC, then you would have a total of 0.1 BTC.

However, if you then want to spend 0.05 BTC, you will need to spend at least 500 of those payments that you received:
500 X 0.0001 BTC = 0.05 BTC.

Since each of them require at least 148 bytes, that means your transaction will be at least:
500 X 148 bytes = 74000 bytes.

The current recommended fee for fast confirmation is 0.00000180 BTC per byte.

Therefore a 74000 byte transaction would require at least:
74000 bytes X 0.00000180 BTC per byte = 0.1332 BTC

That's 0.1332 BTC in transaction fees to spend 0.05 BTC.

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On the other hand, if you had received that entire 0.05 BTC in a single payment, you could spend it with just 148 bytes.

In that case, your fee to spend 0.05 BTC would only be:
148 bytes X 0.00000180 BTC per byte = 0.0002664 BTC.

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When people say that the money you get from faucets is worthless, they mean it literally.

A payment from a faucet of only 0.0003 BTC is actually only worth about 0.0000336 BTC after you subtract out the fees you'll have to pay.

If a faucet pays you less than 0.0002664 BTC in a single payment, then it will cost you more in fees to spend it than it is actually worth.  Meaning, the visit to the faucet actually lost you money.