Shaikh Abdul Ghani Tarablusi al Khalwati (Allah have mercy on him) said,

‘It is from the etiquette (adab) of a murid to be cautious in observing and speaking about the useless issues.

The significance of this may be understood clearly with this incident report. A Shaikh dismissed one of his murid when he came to know that he had destroyed a wine keg he saw in the marketplace. Explaining this dismissal the Shaikh said that the reason was not his action to prevent a vile thing (nahi anil munkar) but his careless use of sight in observing the useless. This would have never occurred if his sight was at his feet (as is recommended, to abstain from seeing useless).’

Tarsih al Jawahir al Makkiyah fi Tazkiya tul Aklaq al mardhiyah, (Urdu), page 125

Similarly, a seeker while in the sacred masjid al Haram Makkah commented on the extravagant use of electric lights, especially to illuminate the minarets, etc.

Shaikh Dr Hafeezullah (Allah have mercy on him) replied,

‘Observing these sorts of things is superfluous and inappropriate use of sight.’

All of us, who aspire to be spiritual seekers, must take a moment and reflect on this.
Furthermore we should ponder, this is in regards to observing the useless. How severe the consequences would be on seeing the sinful things?