This is a tough one. Cigars are a natural product, so there are a myriad of ways you could end up with a crappy stick. It could be over or under humidified, it could be poorly made, it could be in a sick period (cigars can go through additional fermentation after being rolled that leaves them "sick" for a little while), or it could just be made with poor quality tobacco in the first place.
For those of us more seasoned smokers, we have a number of ways we try to mitigate this:
1.
Get your storage right. Make sure you have a suitable environment for your smokes that prevents them from being "shocked" by drastic rH and temp swings. Lots of threads here about starting tupperdores, coolidors, wineadors, or even how to just get a good traditional humidor (which, unless you're going high-end, should be your last resort). If you're already there...
2.
Let 'em rest. Especially for those cigars coming from B&Ms with high rH, and mail order cigars, a little rest will often help ensure the smoke you choose will smoke well. Often online retailers and many B&Ms will keep with cigars at a >70% rH. I personally find nearly all cigars burn too hot and acrid and bitter at a high rH, and much prefer them lower. However, it takes time for a cigar to acclimate to a lower rH. There's debate about "sick" periods with cigars, but many guys here will tell you that a lot of cigars from online vendors do much better with a few months of rest at a proper rH. How long did those two cigars rest in your humi?
3.
Give it a whiff. Check the cigar when you pick it up. If it has an ammonia smell to it, let it rest for a couple months and pick up something else.
4. The above things will help avoid many problems, but some cigars just suck. So
read reviews before buying a stick. Ignore advertisements, look for reviews from well-respected reviewers. Pay less attention to the scores and more attention to the flavor and quality descriptions. Find a reviewer -or a BOTL here- that has a similar palate to yours and follow them.
Also... don't smoke 60rg cigars! I know that sounds snooty, but I've really only had one or two good 60rg cigars. Most just suck. IMHO