An overseer, then, must be above reproach, the husband of one wife, temperate, prudent, respectable, hospitable, able to teach, …
1 Timothy 3:2 (emphasis mine)
To be respectable is to be proper, honorable and appropriate.
This word is only used in one other verse in the New Testament. In 1 Timothy 2:9 women are instructed to adorn themselves in respectable apparel. In other words, their dress should reflect their godliness.
In a similar way, an overseer must demonstrate good behavior that is consistent with godliness. Jesus rebuked the scribes and Pharisees because how they lived was inconsistent with what they taught.
Then Jesus spoke to the crowds and to His disciples, saying: “The scribes and the Pharisees have seated themselves in the chair of Moses; therefore all that they tell you, do and observe, but do not do according to their deeds; for they say things and do not do them.”
Matthew 23:1–3
Paul reminded Timothy that he must watch both his life and his doctrine.
Pay close attention to yourself and to your teaching; persevere in these things, for as you do this you will ensure salvation both for yourself and for those who hear you.
1 Timothy 4:16
An elder is respectable when his life reflects godliness. After all, he needs to be able to say with the apostle Paul:
Be imitators of me, just as I also am of Christ.
1 Corinthians 11:1