title_body: Why do I have such a problem with my conlangs being ugly? This is a perpetual problem I have and I find it quite annoying. Yes, I know its kinda subjective, but that doesn't change the fact that, to me at least, my conlangs are always hideous.
  
  For a recent example, my most recent conlang has agglutinating pronouns. For instance, the word for 'I' is 'ta' and the word for 'we' is 'tai' (pronounced like 'tie', minus the aspiration of course). That's not too bad. The issue is when I add the nominative marker -s: 'tas' and 'tais'. To me, 'tais' just sounds hideous.
  
  In past I think it was because I used the voiceless velar fricative far too often. But even if I don't include the phoneme my language sounds hideous, and artificial to the point that its sounds robotic. Though the latter is probably because I have a hard time NOT making conlangs 'logical'.
  
  There are of course nice-sounding conlangs out there, and even natlangs, but I just can't seem to imitate the sound of any other language for some reason, and I don't get why. And I specialize in phonology, so I don't get why I can't get the sound right. Even if my conlang has the exact same phonemes, allophony, intonation, and phonotactics as a natlang, it will sound completely different and I can't figure out why. I mean, how can I screw up the latter? What am I missing?
upvoted_answer: What you need is to adjust your phonotactics. Since you mention it in your question you apparently know what they are, but you aren't using them to get the sounds you want.
  
  You say you find "tais" to be hideous, but you don't explain why, so let's say you don't like the way that a diphthong sounds in a closed syllable. (If this isn't the case, take this as an example for whatever the problem is.)
  
  Once you've located the problem, you have to determine how to eliminate it by making rules for new phonotactics. You can think of lots of ways:
  
  
  The diphthong becomes a monophthong: tais > tas,  tis or tes in a closed syllable (tas might be problematic since it creates ambiguity with the singular). Or, alternatively, two monophthongs: tais could be [ta.is] instead of [tajs]
  A new consonant could be placed to separate the diphthong: tais could transform into tayis, maybe taus could be tawus (based on a simple rule of adding y before a front vowel and w before a back vowel)
  The diphthong could monophthongize and simple color the next consonant: tais could be pronounced [taɕ]. You could create a pattern with other consonants, e.g. tait > [tac], taid > [taɟ]
  Even if some of these options are problematic in your case (maybe you don't want to "contaminate" your agglutinative language), you could still retain the phonemes /tajs/ and just have some of these options as allophones of it (so e.g. [e] or [e:] could be an allophone of /aj/ in a closed syllable, [ɕ] could be an allophone of /js/)
  
  
  What you need to do is just determine what sounds ugly to you and create phonotactic rules that cover whatever the problem is.