Though the 'Bleeding Love' hitmaker doesn't think the two stars are putting on an act with their raunchy behaviour, she gets upset when she sees her young nieces and goddaughter mimicking their dance moves.
She said: ''I've met them both and that is them - they're not putting on an act and no one is telling them what to do.
''I have a lot of respect for them, but because I have nieces and I've seen my six-year-old goddaughter doing dance moves that she shouldn't, it does not impress me and I tell her to stop.''
Though she loves looking after the children in her life, Leona - who is dating German actor Dennis Jauch - insists she isn't ready for a family of her own yet.
Asked if she feels broody, she told Britain's OK! magazine: ''Not at all. My best friend's just told me she's pregnant and I always thought she'd either have a baby really late or not have one, so that's going to be fun and enough for me. I like godmother and auntie duties.''