I’d definitely recommend using conversion tracking rather than judging a campaign by clicks alone.
For paid traffic, I usually look at the full path: traffic source → clicks → landing page → conversions → CPA/ROI. Adding UTM parameters helps identify where the visitors are coming from, while S2S tracking or a tracker such as Voluum or RedTrack can give you more visibility into which sources, campaigns and placements are actually producing conversions.
The important part is passing the conversion data back to the ad platform/ad network. That way, you can identify the traffic that is generating real results and cut back on sources that are only bringing clicks without conversions.
For me, conversion rate, CPA and ROI are much more useful campaign metrics than CTR alone.